O qual / a qual / os quais / as quais is the formal, agreement-carrying relative pronoun of Portuguese. Unlike que (invariable) and quem (invariable and person-only), o qual inflects for gender and number to match its antecedent. This agreement is its superpower: when a sentence has multiple candidate antecedents and que would be ambiguous, o qual can point precisely. Its main habitat is after longer or more complex prepositions (sobre, contra, segundo, mediante, perante, através de, por causa de), and in non-restrictive clauses where the writer wants to sound elevated or avoid the clunkiness of em que or com que. You will see it often in newspapers, legal writing, academic prose, and formal speeches; less often in casual conversation.
The forms — agreement with the antecedent
O qual is built from the definite article o, a, os, as + the adjective qual ("which"). It behaves like a two-word unit: both parts agree in gender and number with the antecedent.
| Form | Agrees with | Example |
|---|---|---|
| o qual | masculine singular | o livro o qual comprei |
| a qual | feminine singular | a carta a qual recebi |
| os quais | masculine plural | os livros os quais comprei |
| as quais | feminine plural | as cartas as quais recebi |
O projeto, o qual começámos em janeiro, já está concluído.
The project, which we started in January, is already finished.
A proposta, a qual foi apresentada ontem, passou com grande maioria.
The proposal, which was submitted yesterday, passed by a large majority.
Os documentos, os quais assinei na semana passada, já chegaram.
The documents, which I signed last week, have already arrived.
As alterações, as quais discutimos na reunião, serão implementadas em breve.
The changes, which we discussed at the meeting, will be implemented soon.
Use 1: after longer or complex prepositions
This is where o qual really earns its place. With short prepositions like a, de, em, com, por, the relative que is perfectly natural (a casa em que vivo). But with longer prepositions or multi-word prepositions, que sounds awkward or clipped, and native speakers reach for o qual.
The prepositions that most strongly prefer o qual include:
- sobre (on, about)
- contra (against)
- segundo (according to)
- mediante (by means of)
- perante (before, in the presence of)
- durante (during)
- após (after)
- desde (since)
- entre (between)
- através de (through)
- graças a (thanks to)
- por meio de (by means of)
- em virtude de (by virtue of)
- por causa de (because of)
A reunião, durante a qual foram tomadas decisões importantes, durou três horas.
The meeting, during which important decisions were made, lasted three hours.
O livro sobre o qual escrevi a minha tese é agora um clássico.
The book about which I wrote my thesis is now a classic.
Os princípios segundo os quais agimos são claros.
The principles according to which we act are clear.
O acordo mediante o qual chegámos a esta solução foi negociado pelo governo.
The agreement by means of which we reached this solution was negotiated by the government.
O tribunal perante o qual compareceu era federal.
The court before which he appeared was federal.
A janela através da qual se vê o mar está sempre aberta.
The window through which you can see the sea is always open.
Native speakers would find "o livro sobre que escrevi" possible but slightly awkward, and "o princípio segundo que agimos" outright wrong-sounding. With these prepositions, switch to o qual.
Use 2: resolving ambiguity
The second great use of o qual is disambiguation. When a sentence has two possible antecedents and que would be unclear, o qual can point to one or the other through its agreement.
Consider the ambiguous sentence:
Vi a irmã do João, que vai casar-se. (I saw João's sister, who is going to get married.)
Is João getting married, or is his sister? In spoken Portuguese, context and intonation usually sort this out. But in writing, o qual / a qual lets you pin it down:
Vi a irmã do João, a qual vai casar-se.
I saw João's sister, who (the sister) is going to get married. (a qual — feminine, so it's the sister)
Vi a irmã do João, o qual vai casar-se.
I saw João's sister, who (João) is going to get married. (o qual — masculine, so it's João)
The feminine a qual agrees with irmã; the masculine o qual agrees with João. One letter's difference, entirely different meaning. This is o qual's unique contribution — no other Portuguese relative pronoun can disambiguate like this.
Encontrei o filho da minha vizinha, o qual mora em Évora.
I met my neighbour's son, who (the son — masculine) lives in Évora.
Encontrei o filho da minha vizinha, a qual mora em Évora.
I met my neighbour's son, who (the neighbour — feminine) lives in Évora.
Falei com o diretor da escola, a qual está a ser renovada.
I spoke to the headmaster of the school, which (the school) is being renovated.
Falei com o diretor da escola, o qual está a ser substituído.
I spoke to the headmaster of the school, who (the headmaster) is being replaced.
Use 3: formal / literary register
Even where que would be grammatically possible, writers sometimes choose o qual simply for stylistic elevation. This is especially common in:
- News editorials and opinion pieces
- Legal and contractual documents
- Academic writing
- Speeches and formal addresses
- 19th- and early 20th-century literature
A decisão, a qual foi anunciada ontem, suscitou grande polémica.
The decision, which was announced yesterday, provoked great controversy. (formal journalism)
O réu, o qual se declarou inocente, aguarda o julgamento.
The defendant, who declared himself innocent, awaits trial. (legal register)
Os resultados, os quais foram publicados no relatório anual, confirmam a tendência.
The results, which were published in the annual report, confirm the trend. (academic)
A nação, a qual sempre soube resistir, não se renderá.
The nation, which has always known how to resist, will not surrender. (oratory)
In everyday conversation, these sentences would typically use que: "a decisão, que foi anunciada ontem..." — same meaning, less formal. The choice of o qual is a deliberate register move.
Contraction with prepositions
A key detail: when a preposition precedes o qual / a qual / os quais / as quais, normal preposition + article contractions apply. The article part of o qual fuses with prepositions exactly as if it were a bare article.
| Preposition |
|
|
|
|
|---|---|---|---|---|
| de | do qual | da qual | dos quais | das quais |
| em | no qual | na qual | nos quais | nas quais |
| a | ao qual | à qual | aos quais | às quais |
| por | pelo qual | pela qual | pelos quais | pelas quais |
Prepositions like com, sobre, para, contra, entre do not contract — you write them as separate words: com o qual, sobre o qual, para o qual, contra os quais, entre as quais.
A razão pela qual te telefonei é importante.
The reason I called you is important. (por + a qual → pela qual)
O vídeo do qual te falei está no YouTube.
The video I told you about is on YouTube. (de + o qual → do qual)
A empresa na qual trabalho tem sede em Lisboa.
The company I work at is headquartered in Lisbon. (em + a qual → na qual)
Os colegas aos quais enviei o relatório já responderam.
The colleagues I sent the report to have already replied. (a + os quais → aos quais)
O problema sobre o qual escreveste é complicado.
The problem you wrote about is complicated. (no contraction — sobre o qual)
O qual with people: allowed but usually loses to quem
You can use o qual for a person, and it is grammatically fine, but quem after a preposition is more idiomatic for people. O qual for a person feels bureaucratic or legalistic.
O candidato com quem falámos tem boas referências. (natural)
The candidate we spoke with has good references.
O candidato com o qual falámos tem boas referências. (grammatical but stiff)
The candidate with whom we spoke has good references.
Os colegas a quem agradeço ajudaram-me muito. (natural)
The colleagues I thank helped me a lot.
Os colegas aos quais agradeço ajudaram-me muito. (very formal)
The colleagues to whom I give thanks helped me a lot.
For people, default to quem. Reach for o qual when (a) you need to disambiguate, (b) the register is very formal, or (c) the preposition itself is one that dislikes quem (segundo, mediante, etc.).
O qual in non-restrictive clauses (commas)
O qual appears much more often in non-restrictive clauses (with commas) than in restrictive ones. In restrictive contexts, que is nearly always preferred because it is tighter and less formal. Compare:
O livro que comprei está em cima da mesa. (restrictive — que is natural)
The book I bought is on the table.
O livro, o qual comprei ontem, está em cima da mesa. (non-restrictive, formal)
The book, which I bought yesterday, is on the table.
O presidente, o qual pronunciou um discurso emotivo, saudou as famílias.
The president, who delivered an emotional speech, greeted the families.
As reformas, as quais serão debatidas amanhã, visam a modernização do sistema.
The reforms, which will be debated tomorrow, aim at modernizing the system.
O que (masculine singular) versus o qual — different pronouns
Don't confuse two things that look similar:
- o qual — inflected relative pronoun, antecedent is a specific noun.
- o que — relative without an antecedent, meaning what or that which. Also used after prepositions to refer back to an entire clause or idea.
Não entendi o que ele disse. (o que = 'what', no antecedent)
I didn't understand what he said.
Ela tropeçou, pelo que caiu ao chão. (pelo que = 'because of which, so', refers to the whole clause)
She tripped, because of which she fell to the ground. (formal)
A proposta pela qual votámos. (pela qual = 'for which', refers to 'a proposta')
The proposal we voted for.
The first two use o que (neuter, no specific noun antecedent). The third uses pela qual because the antecedent is the feminine noun a proposta.
O qual vs que side by side
Many Portuguese sentences allow either pronoun — the choice is about register and clarity.
| Relative clause | Natural | Formal/disambiguating |
|---|---|---|
| restrictive, simple | a casa que comprei | (a casa a qual comprei) — archaic |
| non-restrictive, short | a Ana, que vive em Braga | a Ana, a qual vive em Braga |
| after de, em, a, com, por (thing) | o tema de que falámos | o tema do qual falámos |
| after sobre, contra, segundo, durante | — | o livro sobre o qual escrevi |
| disambiguating two antecedents | ambiguous with que | o filho da Maria, a qual mora aqui |
| legal/academic register | — | os princípios segundo os quais agimos |
A cidade em que vivo é bonita.
The city I live in is beautiful. (informal, everyday)
A cidade na qual vivo é bonita.
The city in which I live is beautiful. (slightly more formal)
A cidade na qual se realizou o congresso é Porto.
The city in which the conference was held is Porto. (academic tone)
Comparison with English
English which is both a relative and a question word, and it can appear freely in both restrictive and non-restrictive clauses. Portuguese o qual corresponds only to the relative which (never the interrogative) and is restricted mostly to non-restrictive clauses and preposition-governed contexts.
| English | Portuguese |
|---|---|
| the book I bought | o livro que comprei (not o qual) |
| the book, which I bought yesterday | o livro, o qual comprei ontem (or que) |
| the topic about which I wrote | o tema sobre o qual escrevi |
| the reason for which I came | a razão pela qual vim |
| the window through which I climbed | a janela através da qual trepei |
| the sister (of X), who is getting married | a irmã (de X), a qual vai casar-se (disambiguating) |
Common mistakes
❌ O livro o qual comprei está em cima da mesa.
Incorrect as everyday style — in a restrictive relative clause, use 'que': 'o livro que comprei'.
✅ O livro que comprei está em cima da mesa.
The book I bought is on the table.
❌ A pessoa a qual falei era a rececionista. (person)
With people after a preposition, prefer 'a quem' over 'a qual'.
✅ A pessoa a quem falei era a rececionista.
The person I spoke to was the receptionist.
❌ O tema sobre que escrevi a tese. (awkward with 'sobre')
With the preposition 'sobre', use 'sobre o qual'.
✅ O tema sobre o qual escrevi a tese.
The topic I wrote my thesis on.
❌ As casas os quais compraram são antigas.
Incorrect agreement — 'as casas' is feminine plural, so it must be 'as quais', not 'os quais'.
✅ As casas as quais compraram são antigas.
The houses they bought are old.
❌ A razão por a qual vim.
Incorrect — 'por + a qual' must contract to 'pela qual'.
✅ A razão pela qual vim.
The reason I came.
❌ O problema da qual falámos não existe.
Incorrect agreement — 'problema' is masculine (despite the -a ending), so it must be 'do qual', not 'da qual'.
✅ O problema do qual falámos não existe.
The problem we talked about doesn't exist.
❌ Vi a irmã do João, o qual vai casar-se, querendo dizer a irmã.
Ambiguity trap — 'o qual' agrees with João (masculine). If you mean the sister, use 'a qual'.
✅ Vi a irmã do João, a qual vai casar-se.
I saw João's sister, who (the sister) is getting married.
Key takeaways
- O qual / a qual / os quais / as quais is a variable relative pronoun that agrees in gender and number with its antecedent.
- Its principal uses: after longer or multi-word prepositions, in non-restrictive clauses, in formal/literary register, and to resolve ambiguity between candidate antecedents.
- Bare o qual (no preposition) in a restrictive clause is archaic — use que instead.
- With short prepositions (a, de, em, com, por), que is natural; o qual is a more formal alternative.
- With longer prepositions (sobre, contra, segundo, durante, mediante, perante, através de), o qual is almost mandatory.
- Normal contractions apply: de + o qual → do qual, em + a qual → na qual, a + os quais → aos quais, por + a qual → pela qual.
- For people after a preposition, quem is the everyday choice; o qual works but feels stiff.
- Its unique strength is the agreement-based disambiguation that neither que nor quem can provide.
Related Topics
- Relative Pronoun Que (The Most Common)A2 — The workhorse relative pronoun of Portuguese — used for people, things, and concepts, as subject or direct object of the relative clause
- Relative Pronoun Quem (Referring to People)B1 — The relative pronoun used specifically for people — mostly after prepositions or as a free relative meaning 'whoever'
- Relative Pronoun Cujo (Whose — Possession)B2 — The possessive relative pronoun — agrees with the thing possessed, not the possessor. Formal and rare in speech.
- Relative Onde (Where)A2 — The relative pronoun used for place — replaces 'em que' or 'no qual' in locative relative clauses
- Pronouns After Prepositions (Mim, Ti, Si, Ele, Ela...)A2 — The full paradigm of prepositional pronouns in European Portuguese — mim, ti, si, ele, ela, nós, vós, eles, elas — and how they work after every preposition except 'com'