The Qatar night race winner, who has only finished one of the three races since - in ninth position - snatched the top spot from Britain's Bradley Smith during the final minute of the half hour session.
Smith fought back to close to within 0.099secs of the Spaniard's Aspar Aprilia, while Stefan Bradl snatched third place on his last lap. Championship leader Simone Corsi completes the front row, which could prove vital for Saturday's second session given the ever-present threat of rain.
Less fortunate was Danny Webb, who suffered a huge highside with eight minutes to go. The Aprilia rider landing heavily on his back and being left in obvious pain.
First qualifying - Le Mans:
1. Gadea (Aprilia)
2. Smith (Aprilia) +0.099secs
3. Bradl (Aprilia) +0.195secs
4. Corsi (Aprilia) +0.196secs
5. di Meglio (Derbi) +0.441secs
6. Rabat (Honda) +0.829secs
7. Espargaro (Derbi) +0.970secs
8. Olive (Derbi) +1.017secs
9. Terol (Aprilia) +1.088secs
10. Cortese (Aprilia) +1.222secs
12. Redding (Aprilia) +1.459secs
19. Webb (Aprilia) +1.927secs
