I have gathered from various sites/resources, the following rules concerning the preposition “o” which, when its meaning is “about”, is always followed by the prepositional case (предложный падеж):

1. before any hard vowel (а, и, о, у, э), always use "об";

2. before any consonant or any soft vowel (е, я, ю), always use "о";

3. "обо" would be only used in the following 6 expressions: -

  • обо мне : about me;
  • обо всех: about everybody (pronoun);
  • обо всём: about everything (pronoun) or about the whole of something (i.e. masculine and neuter adjectives);
  • обо всей: about the whole of something, i.e. the feminine adjective;
  • обо что-то : about something;
  • обо всяком/всякой/всяких… : about any of something, i.e. the masc.+neuter/feminine/plural adjective.

4. Exceptions: when “о” does not mean “about” but “against”, it is then followed by the accusative case, and there are a limited number of exceptions to the above rules, e.g. об пол (against the ground), об руку (against the arm), об стену (against the wall) – in all these three cases, об goes in front of a consonant so rule 2 is not respected. To be noted that in this meaning, we could also find accusative constructions such as обо всего …, обо весь …, обо всё …, обо всю …, обо всех …, and обо все… corresponding respectiveley to masc. animated, masc. unanimated, neuter, feminine, plural animated and plural unanimated.

My question is twofold :

a) are the above rules really exhaustive and contemplating all possible cases, especially the third one, or could we think of other situations where обо would be used?

b) are the 3 exceptions mentioned under 4, when “о/об” means “against”, the only 3 exceptions to rules 1 to 3 or are there other cases where об could be used before a consonant when meaning “against” ? For example, should we say for “against the cupboard”: о шкаф or об шкаф ?

Thank you

  • 1
    Обо что-то is accusative and should go under 4. Commented Apr 21, 2022 at 7:42
  • Thank you @Sergey Slepov, so does обо что-то mean against something ? Would it require after it or could it just stand on its own ? Thank you again
    – Xavier
    Commented Apr 22, 2022 at 9:42
  • What is "hard vowel" and in what sense и is hard?
    – Anixx
    Commented May 13, 2022 at 17:39
  • I would say "об что-то" but "обо что".
    – Anixx
    Commented May 13, 2022 at 17:42
  • обо всего and обо все (not ё) are wrong.
    – Anixx
    Commented May 13, 2022 at 17:45

2 Answers 2


The prepositions o, oб , обо take the prepositional and accusative cases.

Обо is used with pronouns in the accusative: обо что(что--нибудь что-то, что-либо),

with the prepositional :обо мне,

With both the accusative and the prepositional:(весь) обо всё, обо всём, обо всю, обо всей, обо все, обо всех.

With the prepositional case, we use o before a consonant, об before a vowel.

О папе, юле, ели, яблоке. Об Азии, улице, отце, иголке, эпохе.

With the accusative, we use об before a vowel:

Об арку, угол, эстакаду, иголку.

And before consonants, we use either o or об.

О стену, об стену, о забор, об забор, о тротуар, об тротуар,о шкаф, об шкаф(to be continued)

To remember: о нём, о ней, о них, об него, об неё, об них.

And idioms should be memorized: рука об руку

The source is Орфоэпический словарь русского языка под ред. Аванесова.


I have some additional notes on "обо". There are several mistakes/typos in your initial lists, and I would like to sum them up with examples.

There are two cases in which "обо" is used:

  1. with the meaning "about" (prepositional case)
  2. with the meaning "against"/"upon" (accusative case)

In both cases, the form "обо" represents an exception, so there's only a limited number of expressions where it can be used. Let's break it down:

1. "обо" = about (prepositional case)

  • обо мне (about me)
  • обо всех (about everyone)
  • обо всём (about everything, from original "всё")
  • обо всём X (about the whole X, from original "весь")
  • обо всей X (about the whole X, from original "вся" - the feminine of "весь")

*** additionally, it's possible to use it with "всякие" (various) or "многие" (many), but I would prefer "о всяких", "о многих".

2. "обо" = against / upon (accusative case)

  • обо что? (against what?)
  • обо что-то (against something)
  • обо всё (against everything)

*** the following two are rare, both of them are usually used with "о" instead:

  • обо всего X (against the whole X, from original "весь", only used for animated objects)
  • обо всю X (against/upon the whole X, from original "вся")

Please note that all the other examples in your "обо"-lists are incorrect! You can't say "обо весь", "обо все", and some of the other examples you listed are just mixed up between the cases.

FYI: when "обо" is used in the meaning "against/upon" there are very few verbs that can be used with it:

  • удариться обо что-то (to hit oneself against something, run against something)

Обо что ты ударился?

  • споткнуться обо что-то (to trip over something)

Я обо что-то споткнулась.

  • испачкаться обо что-то (to get dirty with something)

Я испачкалась обо всё это дерьмо. (sorry, couldn't think of another example)

  • вытереть обо что-то (to wipe with something) or обтереться обо что-то (to rub against something)

Он обтёрся обо всего кота. (the whole situation is a bit weird, but I can't think of a normal case in which "обо всего" would be used naturally)

  • точить обо что-то (to sharpen with something)

Кошка успела поточить когти обо всю мою мебель.

... and maybe some other verbs that I couldn't think of.

And one more thing: above, I listed "обо всего" which, as I mentioned, only works with animated objects. If you need more information on the difference between accusative forms for masculine animate and inanimate objects, here's a link: https://www.ruspeach.com/learning/5109/

As for the difference between "о"/"об", I agree with the previous comment, but there are several more examples I can add to the second "об"-list (accusative case). With the verbs like "вытереть" or "удариться" I would normally use "об" with these pronouns:

  • об меня (against/upon me)
  • об тебя (against/upon you)
  • об себя (against/upon oneself)
  • об неё (against/upon her)
  • об него (against/upon him)

With other pronouns and nouns starting with consonants, you can usually choose between "о"/"об" ("Ударился об шкаф"/"Ударился о шкаф" and "Вытер об нас ноги"/"Вытер о нас ноги" all sound correct to me). I tend to use "об" in most cases to emphasize the difference from "о" with the meaning "about".

  • Another excellent answer! You must live in an English-speaking country, no?
    – CocoPop
    Commented Aug 11, 2022 at 13:04
  • No.... It's a bit awkward to say it, but I live in Russia
    – ALÖ
    Commented Aug 11, 2022 at 13:23
    – CocoPop
    Commented Aug 11, 2022 at 13:26
  • Probably all those years of watching British crime dramas finally bore fruit... haha
    – ALÖ
    Commented Aug 11, 2022 at 13:43
  • 1
    American??? Must be Faulkner's influence... And please send me the link to your Telegram, I'd love to join!
    – ALÖ
    Commented Aug 11, 2022 at 14:16

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