Are that a Russian or Austria uniform?

Hello!

Are that a Russian or Austria uniform and which regimen?

Doesn't look Russian to me. Can't say if it's Austrian: what led you to believe it could be?

Some told for me to this is possible a uniform of the Grenadier Regiments!

interesting decorations on his left.
could we have a better picture of those ?
and of the cap/helmet ?

Nothing on the backside of the painting

It does not look very Austrian.
Did you try ?
http://www.grosser-generalstab.de/tafeln/knoetel.html

No, the uniform does not look Austrian. I don't know about Russian.

For moment have I not better picture than what I have here and will trying to making some better after holiday!

The uniform style is anywhere between about 1805 and 1855.  Russian or Austrian?  The problem with it being Russian is that the regulations for Russian service stripes place them on the left sleeve, not the right, and they are chevrons, not single diagonal slashes.

To judge by the gentleman's haircut and moustache, I would put the picture at 1850-ish.

Ann