This study investigates the photocatalytic decomposition of acetic acid and its reaction mechanism over WO3-supported ordered intermetallic PtPb nanoparticle (NiAs-type structure, P63/mmc, a=0.4259 nm; c=0.5267 nm) (PtPb NPs/WO3) co-catalysts under an oxygen-rich atmosphere and visible light. We rationally designed and synthesized the ordered intermetallic nanoparticle on WO3 co-catalysts by a photodeposition and polyol method. Remarkably enhanced activities were observed for the synthesized PtPb NPs/WO3 catalyst toward the decomposition of organic compounds compared to pure WO3 and WO3-supported individual Pt co-catalysts. (C) 2015 Elsevier B.V. All rights reserved.