Opinion of/about/on him?

Fatimah:

"of" is more common, especially when you modify "opinion."
We have a high opinion of him.

Thanks for answering. Could you tell me whether "opinion about/on" is possible at all, as I have heard people using such constructions on t.v?

It is very common to use "about" for topics. "of" is mostly used for people.
But it is not wrong to say "about him" or "about her."

Most people have strong opinions about their government's policies. (We don't use "of" in this context.)

Thanks for answering. Is 'opinion on' wrong?

fatimah0786Thanks for answering. Is 'opinion on' wrong?

No. Here is a very common collocation:
The group had widely differing opinions on the benefits of the health care law.

Thanks for answering. Could you tell me the difference between 'opinion on' and 'opinion about' as both seem the same to me in meaning?

There is no semantic difference. It is just that certain collocations are preferred, or more common, in certain contexts.
Prepositions are notorious in this regard.