There are dozens if not hundreds of so called "cool down" apps on the market, but really all they do is close many of your running apps. You can try one or 2 of those apps to see if it helps. But I think it's pretty much like others have said, you gotta stop what you're doing and let it cool off. Unless, you feel that it's overheating with just "normal" use (i.e, nothing too drastic and power consuming such as gaming, video watching....etc) in which case I'd recommend having it looked at. How old is it?