Full Declension of the Reflexive: sebe, sobě, sebou

You already know the little reflexive words se and si — the ones that cling to verbs in myje se (he's washing) and koupil si (he bought himself). Those are the unstressed, short forms. But the reflexive pronoun has a full set of long forms too — sebe, sobě, sebou — and you reach for them whenever the reflexive needs to stand on its own two feet: after a preposition, or under stress. This page lays out the whole paradigm and, crucially, when each form is the only correct choice.

The paradigm: no nominative

The reflexive pronoun is defined by what it can't do: it can never be the subject of its own clause (you can't "do something to the subject" when the reflexive is the subject). So there is no nominative form at all.

Two things to read off this table immediately. First, sebe covers genitive and accusative, sobě covers dative and locative, and sebou is the instrumental — three forms doing all the work. Second, the locative and instrumental have no short form: there simply is no clitic for them, so after a preposition like o (about) or s (with) you are forced to use sobě and sebou.

Rule 1: after a preposition, always the long form

A preposition can never be followed by a clitic. So the moment a reflexive sits behind a preposition, it must surface as sebe / sobě / sebou, never se / si.

Notice how the choice of case follows the preposition's government: o and na and pro and mezi each demand their usual case, and the reflexive simply supplies the matching long form — o sobě (locative), na sebe (accusative), pro sebe (accusative), mezi sebou (instrumental).

Rule 2: the fixed idiom s sebou

The single phrase learners most often get wrong is s sebou — "with oneself," the everyday way to say you're taking something with you or ordering food to go. The spelling is fixed as s sebou, with a bare s, even though the instrumental of the personal pronoun já vocalizes to se mnou. The reflexive does not vocalize: it is s sebou, not "se sebou."

Rule 3: the long form for stress and contrast

Even with no preposition, you switch to the long sebe / sobě when the reflexive carries emphasis or is contrasted with someone else. A clitic can't be stressed, so the long form is the only way to put weight on it.

The intensifier sám (oneself) frequently teams up with the long reflexive to mean "one's very self." sám agrees with the subject in gender and number — sám (masculine), sama (feminine), sami (animate plural):

Reflexive vs personal pronoun: a meaning you can't fake

Here is where the reflexive earns its keep, and where the English-speaker error is most costly. When the thing being referred to is the subject, you must use the reflexive. Swapping in a personal pronoun (něm, ho, mu) does not just sound off — it changes who you're talking about.

• Petr mluví o sobě. = Petr talks about himself. (the subject Petr)
• Petr mluví o něm. = Petr talks about him — some other man.

English uses "himself" vs "him" for exactly this contrast, so the logic is familiar; the mistake is forgetting that Czech makes you spell it out with sobě rather than něm.

Common mistakes

The first error is trying to put a clitic after a preposition:

The second is vocalizing the fixed idiom:

The third is substituting a personal pronoun when the referent is the subject:

The fourth is using the accusative sebe where a dative sobě is required:

Key takeaways

• The reflexive has no nominative; its long forms are sebe (gen/acc), sobě (dat/loc), sebou (instr).
• The locative and instrumental have no clitic, so after a preposition you always use sobě / sebou.
• Use the long form after any preposition and under stress/contrast; use the clitics se / si for unstressed objects glued to the verb.
• s sebou ("with oneself," "to go") is a fixed spelling — never "se sebou."
• The reflexive tracks the subject and is the same for every person; replacing it with němu/ho/ni changes the meaning to someone else.