The correct pronoun usage for: Natalia a is better cook than I?

It is difficult to determine whether to use "I" or "me" as a pronoun in some instances, and to be quite honest, in most cases you can use either- at least in terms of producing a sentence that makes sense and will be understood.

In the example you have given: Natalia is better cook than I, the first thing to mention is that you need to add an 'a' in between 'better' and 'cook', so that it reads 'Natalia is a better cook than I'. After that, I'd say it was spot on, and you are using I as the pronoun correctly.

There is definitely a grey area here, however, as I firmly believe you could have said 'Natalia is a better cook then me' without it making any less sense, or seeming grammatically inaccurate. Use of other pronouns is a lot clearer...

For example, you might say "Natalia is a great cook, I enjoy her food" but you couldn't say "Natalia is a great cook, I enjoy she food".

The official guide for using the personal pronouns of 'I' and 'me' is as follows:

• Use the pronoun 'I' when it is the subject of a verb, and the pronoun 'me' when it is the object of a verb.

It sounds a little bit theoretical to understand, but makes sense when you see a few examples and start to get your head around it.