The 19-year-old, who finished tenth at the Qatar season opener, took control early in the half hour session and then returned to the top in the closing stages as he edged out team-mate Simone Corsi by 0.259secs.
Qatar pole sitter Bradley Smith finished the session third, having had his last lap ruined when he ran wide while trying to negotiate backmarkers. Stefan Bradl completed the all-Aprilia provisional front row.
Round one winner Sergio Gadea and reigning world champion team-mate Gabor Talmacsi had a tougher time, after finishing a tight session in tenth and eleventh places.
Wild-card Axel Pons, son of former double 250 world champion and
MotoGP team owner Sito, qualified a provisional 30th, riding a third Jack & Jones Aprilia.
First qualifying - Jerez:
1. Terol (Aprilia)
2. Corsi (Aprilia) +0.259secs
3. Smith (Aprilia) +0.292secs
4. Bradl (Aprilia) +0.334secs
5. Espargaro (Derbi) +0.494secs
6. Bonsey (Aprilia) +0.542secs
7. di Meglio (Derbi) +0.590secs
8. de Rosa (KTM) +0.618secs
9. Redding (Aprilia) +0.750secs
10. Gadea (Aprilia) +0.768secs
14. Webb (Aprilia) +0.936secs
