The Portuguese saw his side climb to third in the Premier League on Saturday with a 3-0 triumph at Upton Park, where Oscar's strike was sandwiched by a Frank Lampard double.
Mourinho was particularly impressed with the Brazil international, who notched his sixth goal in all competitions this season.
"Oscar is fantastic - it doesn't matter where, in the middle, on the sides; he works hard, he recovers balls and he presses high and gives a difficult time to the opponents and when he has the ball he's able to assist and able to score," Mourinho said.
"He's a very young kid. It's not easy to succeed in this football country when you have the talent he has and the physical ability he doesn't have because he's a fragile boy as you can see. That talent is amazing and he can only improve."
Striker Samuel Eto'o also earned the praise of his boss, who is insistent the 32-year-old still has the quality that elevated him to global stardom with Barcelona and Inter.
"Eto'o holds the ball, waits for support. He's not obsessed with scoring goals, he's obsessed with playing football," Mourinho said.
"Without being the fast killer that he was four or five years ago the quality is there and he's giving a big contribution for the way we want to play."
