Interrogative Pronouns: tko, što, koji | Croatian Grammar

Croatian asks "who?", "what?", and "which?" with three core words: tko, što, and koji. The first thing English speakers must absorb is that these are not frozen little question words — they are pronouns that take case. Just as a noun changes shape according to its role in the sentence, so does the question word that asks about that role. "Who do you see?" puts tko into the accusative (Koga vidiš?); "What are you talking about?" puts što into the locative (O čemu govoriš?). And crucially, when a preposition is involved, the preposition comes first, glued to the question word — Croatian never strands prepositions the way English does.

tko — "who" (always about people)

Tko asks about a person. It is grammatically masculine singular, no matter who the answer turns out to be, so the verb and any agreeing words go masculine singular. Here is its full declension:

Case	Form	Asks…
Nominativ	tko	Who? (subject)
Genitiv	koga	Whose? / Of whom?
Dativ	komu (kome)	To whom?
Akuzativ	koga	Whom? (object)
Lokativ	kome (komu)	About whom?
Instrumental	kim(e)	With whom?

Two things to notice. The genitive and accusative are identical — both koga — exactly the animacy pattern you see in masculine nouns and adjectives, because tko is inherently animate. And the instrumental has a short form kim and a longer kime; after a preposition the form kim is the everyday choice (s kim).

Tko je ovo napisao?

Who wrote this? — nominative 'tko', subject; verb is masculine singular 'napisao'.

Koga si vidio na placu?

Whom did you see at the market? — accusative 'koga', direct object.

Komu da pošaljem poruku?

To whom should I send the message? — dative 'komu'.

S kim ideš na koncert?

Who are you going to the concert with? — instrumental 'kim' after 's'; the preposition comes first.

O kome to govoriš?

Who are you talking about? — locative 'kome' after 'o'; never *Kome about.

što — "what" (about things)

Što asks about a thing, an idea, or an action. It is grammatically neuter singular. Its declension is built on a different stem (č-) in the oblique cases:

Case	Form	Asks…
Nominativ	što	What? (subject)
Genitiv	čega	Of what? / What … of?
Dativ	čemu	To/at what?
Akuzativ	što	What? (object)
Lokativ	čemu	About what?
Instrumental	čime	With/by what?

Here the nominative and accusative are identical (što) — the neuter pattern — while the oblique forms switch to the č- stem: čega, čemu, čime. The dative and locative collapse into one form, čemu.

Što se dogodilo?

What happened? — nominative 'što', subject; neuter verb 'dogodilo se'.

Čega se bojiš?

What are you afraid of? — genitive 'čega', because 'bojati se' takes the genitive.

Čemu se smiješ?

What are you laughing at? — dative 'čemu' with 'smijati se'.

O čemu razmišljaš?

What are you thinking about? — locative 'čemu' after 'o'.

Čime ćeš otvoriti konzervu?

What will you open the can with? — instrumental 'čime', the means/tool.

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Many Croatian verbs assign a case other than the obvious one, and the question word inherits it. Bojati se ("to fear") takes the genitive, so "what are you afraid of?" is Čega se bojiš? — not the accusative. When you learn a verb's case, you simultaneously learn how to question its object.

koji / koja / koje — "which, what (kind of)"

Koji narrows a choice within a known set: "which one?". Unlike tko and što, it agrees with the noun it asks about in gender and number, and it declines like a pronominal adjective — sharing the -og, -om, -im oblique endings you met with the demonstratives (see demonstrative declension).

Koji autobus ide u centar?

Which bus goes to the centre? — masculine 'koji' agreeing with 'autobus'.

Koju knjigu čitaš?

Which book are you reading? — feminine accusative 'koju' with 'knjiga'.

U kojem si gradu odrastao?

Which city did you grow up in? — locative 'kojem' after 'u'; preposition first.

Koje boje je tvoj auto?

What colour is your car? — 'koje boje', genitive 'boje' (lit. 'of which colour').

kakav, čiji, koliko

Three more high-frequency question words round out the set:

kakav / kakva / kakvo — "what kind of?", asking about quality, not identity. It declines like an adjective. Kakav asks for a description; koji asks you to pick from known options.
čiji / čija / čije — "whose?". Also adjectival, agreeing with the possessed thing.
koliko — "how much / how many?". It is indeclinable and governs the genitive of what it counts: koliko ljudi ("how many people"), koliko vremena ("how much time").

Kakav je to film, smiješan ili ozbiljan?

What kind of film is it, funny or serious? — 'kakav' asks for a quality.

Čija je ovo jakna?

Whose jacket is this? — feminine 'čija' agreeing with 'jakna'.

Koliko ljudi dolazi večeras?

How many people are coming tonight? — 'koliko' + genitive plural 'ljudi'.

Koliko košta ova kava?

How much does this coffee cost? — 'koliko' as 'how much'.

tko for people, što for everything else

English lets "what" stray onto people in some questions ("What is she?" asking about a profession) and uses "who" loosely. Croatian draws the line more firmly: tko is for people (and, by extension, for beings you treat as persons — God, named pets), and što is for things, animals in the general case, abstractions, and actions. Asking Što je ona? would be asking what kind of thing she is; to ask about her job you say Čime se ona bavi? ("What does she do?", literally "with what does she occupy herself"). Keep the human/non-human boundary clean and you will pick the right word automatically.

Tko je ta gospođa pokraj tebe?

Who's that lady next to you? — a person → 'tko'.

Što je to u tvojoj ruci?

What's that in your hand? — a thing → 'što'.

Čime se baviš?

What do you do (for a living)? — profession is asked with instrumental 'čime' + 'baviti se', not 'što'.

The preposition comes first — no stranding

This is the single biggest structural difference from English. English happily strands its prepositions at the end of the clause: "Who are you going with?", "What are you talking about?". Croatian forbids this. The preposition and the question word travel together at the front: S kim ideš?, O čemu govoriš?. Putting the preposition anywhere else, or leaving it dangling, is ungrammatical.

Za koga je ovaj poklon?

Who is this present for? — 'za koga' fronted; never *Koga za.

Na što misliš?

What are you referring to? — 'na što' fronted together.

Do kada radiš danas?

Until when are you working today? — even adverbial questions front the preposition: 'do kada'.

Question word order

A wh-question in Croatian opens with the question word (plus its preposition), followed immediately by the verb and the clitics. There is no "do-support" as in English — no auxiliary "do/does/did" — the verb itself carries the question.

Što radiš?

What are you doing? — question word + verb, no auxiliary.

Koga si zvao jučer?

Whom did you call yesterday? — 'koga' + clitic 'si' + participle; no 'did'.

Common mistakes

❌ Tko vidiš?

Incorrect — 'who' as the object must be accusative 'koga', not nominative 'tko'.

✅ Koga vidiš?

Whom do you see? — accusative 'koga'.

❌ Što se bojiš?

Incorrect — 'bojati se' takes the genitive, so 'što' must become 'čega'.

✅ Čega se bojiš?

What are you afraid of? — genitive 'čega'.

❌ Kim ideš s?

Incorrect — the preposition can't be stranded; it must come first: 'S kim ideš?'

✅ S kim ideš?

Who are you going with? — 's kim', preposition fronted.

❌ Koliko ljudi su došli?

Watch the agreement and case — 'koliko' takes the genitive 'ljudi' and the verb is normally neuter singular.

✅ Koliko je ljudi došlo?

How many people came? — 'koliko' + genitive 'ljudi', neuter singular verb.

❌ Koji knjigu čitaš?

Incorrect — 'koji' must agree with feminine 'knjiga' in the accusative: 'koju'.

✅ Koju knjigu čitaš?

Which book are you reading? — feminine accusative 'koju'.

Key takeaways

tko ("who", people) declines tko / koga / komu / koga / kim(e) / kome; genitive = accusative (koga); it is treated as masculine singular.
što ("what", things) declines što / čega / čemu / što / čime / čemu; nominative = accusative (što); it is neuter singular, with the oblique č- stem.
koji / koja / koje ("which") agrees with its noun and declines pronominally (-og, -om, -im).
kakav ("what kind"), čiji ("whose"), and indeclinable koliko ("how much/many", + genitive) complete the set.
The verb governs the case, so the question word inherits it; and the preposition always comes first — Croatian never strands it.

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