F 1 -ATPase has three interacting catalytic sites and shows complicated kinetics. Here, we report reconstitution of a complex, most likely composed of one α subunit and one β subunit, with a single catalytic site from thermophilic Bacillus PS3 F 1 -ATPase on the solid surface. The complex has an ATPase activity which obeys a simple non-cooperative kinetics with a K m (ATP) of 70 μM and a V m a x of 0.1 unit/mg. Different from F 1 -ATPase, the complex is not inactivated by 7-chrolo-4-nitrobenzofrazan. Thus, the inherent activity attributable to a single catalytic site unaffected by other catalytic sites of F 1 -ATPase is characterized.