Dempsey scored an impressive hat-trick in Fulham's 4-0 win over Charlton Athletic in the FA Cup 3rd round on Saturday.
The Dutch manager applauded the attacking midfielder's hunger for the game as well as his versatility as a player.
"He's an American boy and every training session he wants to win. He's got the eye of the tiger," said Jol.
"He can play in a 4-4-2 and he can play from midfield as well. He plays wide but he's not a wing player and now he's more like an attacking No10 and he plays there for the national team as well.
"It's a great joy to know he can play in different systems."
Dempsey joined Fulham in 2007 from MLS side New England Revolution.