The BMW Motorrad rider set a time of a minute 57.491 in the second session, which put him just over half a second clear of Briton Tom Sykes on the factory Kawasaki.
Melandri is fourth in the standings, nine points behind third-placed Sykes.
Series leader Max Biaggi could only put his Aprilia sixth, while second-placed Brit Jonathan Rea was down in 11th on the factory Honda.
Ducati Althea’s Carlos Checa was third ahead of Briton Leon Haslam (BMW Motorrad) and Irishman Eugene Laverty (Aprilia).
QP1
BMW Motorrad's Marco Melandri led first qualifying practice for the World Superbike races at Motorland Aragon, Spain.
Series leader Max Biaggi was second on the Aprilia with Briton Tom Sykes on the factory Kawasaki third.
Ireland’s Eugene Laverty (Aprilia) was fourth ahead of Briton Leon Haslam (BMW Motorrad).
Haslam’s compatriot Jonathan Rea, second in the standings, was down in 14th on the factory Honda.
Results (first timed/second timed/combined)
1 M. MELANDRI ITA BMW Motorrad Motorsport BMW S1000 RR 1'58.608 1'57.491 1'57.491
2 T. SYKES GBR Kawasaki Racing Team Kawasaki ZX-10R 1'59.123 1'58.005 1'58.005
3 C. CHECA ESP Althea Racing Ducati 1098R 2'00.401 1'58.018 1'58.018
4 L. HASLAM GBR BMW Motorrad Motorsport BMW S1000 RR 1'59.396 1'58.144 1'58.144
5 E. LAVERTY IRL Aprilia Racing Team Aprilia RSV4 Factory 1'59.263 1'58.241 1'58.241
6 M. BIAGGI ITA Aprilia Racing Team Aprilia RSV4 Factory 1'58.973 1'58.282 1'58.282
7 L. CAMIER GBR FIXI Crescent Suzuki Suzuki GSX-R1000 2'00.147 1'58.612 1'58.612
8 A. BADOVINI ITA BMW Motorrad Italia GoldBet BMW S1000 RR 1'59.751 1'58.641 1'58.641
9 M. FABRIZIO ITA BMW Motorrad Italia GoldBet BMW S1000 RR 1'59.770 1'58.690 1'58.690
10 D. GIUGLIANO ITA Althea Racing Ducati 1098R 2'00.514 1'58.700 1'58.700
11 J. REA GBR Honda World Superbike Team Honda CBR1000RR 2'00.617 1'58.708 1'58.708
12 S. GUINTOLI FRA Team Effenbert Liberty Racing Ducati 1098R 2'00.640 1'58.710 1'58.710
13 C. DAVIES GBR ParkinGO MTC Racing Aprilia RSV4 Factory 2'00.146 1'58.884 1'58.884
14 J. SMRZ CZE Liberty Racing Team Effenbert Ducati 1098R 2'02.032 1'58.989 1'58.989
15 L. ZANETTI ITA PATA Racing Team Ducati 1098R 2'01.965 1'59.003 1'59.003
16 L. BAZ FRA Kawasaki Racing Team Kawasaki ZX-10R 2'00.690 1'59.017 1'59.017
17 D. SALOM ESP Team Pedercini Kawasaki ZX-10R 2'02.616 1'59.474 1'59.474
18 H. AOYAMA JPN Honda World Superbike Team Honda CBR1000RR 2'01.827 1'59.686 1'59.686
19 N. CANEPA ITA Red Devils Roma Ducati 1098R 2'00.615 1'59.811 1'59.811
20 M. BERGER FRA Team Effenbert Liberty Racing Ducati 1098R 2'01.151 2'00.164 2'00.164
21 J. HOPKINS USA FIXI Crescent Suzuki Suzuki GSX-R1000 2'00.570 2'00.245 2'00.245
22 L. MERCADO ARG Team Pedercini Kawasaki ZX-10R 2'02.630 2'00.975 2'00.975
23 N. BRIGNOLA ITA Grillini Progea Superbike Team BMW S1000 RR 2'07.213 2'03.823 2'03.823
