Whether Jupiter has solid surface? What is its expected surface temperature?

Here is all you ever wanted to know about Jupiter.
http://space-facts.com/jupiter/
Its surface temp is - 108oC (2 1/2 times colder than anywhere I've ever lived.)
It has a dense atmosphere mostly hydrogen.
Its inner core is made mostly of hydrogen compounds.

Google strikes again.

Actually pretty darn hot at the surface.
The theoretical structure is a small rocky core which was the seed point ofr the runaway collection of gasses.
Now as it grew it heated due to compression - that is a lot of gas so a lot of initial heat.
Now the pressure is so incredible that you get methane rain and sleet at the top - but (the chemistry gets very strange) you get liquid Hydrogen condensing under extreme temperature and pressure - hundreds of celsius and pressure we can not create.

A layer of liquid Hydrogen overlying (probably) a solid surface of metallic Hydrogen. For a given value of solid. You would find it hard on first contact but then the pressure and gravity and strange chemistry would mean the solid Hydrogen would interpenetrate with pretty much any other solid - which sinks as every atomic pore fills with Hydrogen.

Yes, darn cold.