Why does car stall when hot?

There are so many reasons, you really should provide more info. First, what kind of car is it? Is it overheating? Because it could be the vehicles computer stradegy shutting down the engine to protect it. Does the car feel like it's running out of gas? The fuel pump could be failing when it gets hot. Does the car suddenly cut off, like someone turned the key off? It could be the ignition system failing when hot.