We report shape-dependent localized surface plasmon enhanced photocatalytic effect of ZnO nanorods decorated with Ag nanostructures. The plasmonic ZnO photoelectrode modified by Ag nanoprisms exhibits a significant enhancement in photoelectric conversion with a maximum photoconversion efficiency of 1.45%. The photocurrent intensity (at 0.5 V vs. Ag/AgCl) of ZnO-Ag nanoprisms is 3.1 and 10 times greater than that of ZnO-Ag nanoparticles and as-grown ZnO nanorods, respectively. Moreover, ZnO-Ag nanoprisms showed a fast photoresponse due to the fast transport of photogenerated charge carriers in ZnO nanorods with a low recombination rate. It is suggested that the mechanism of photocatalytic enhancement by Ag nanoprisms is mainly ascribed to the significantly enhanced plasmonic 'hotspots' in sharp tips of nanoprisms. Such shape-dependent localized surface plasmon effect is further confirmed by FDTD simulation, which revealed that Ag nanoprisms showed stronger electromagnetic field intensity than that of Ag nanoparticles. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.