High-surface-area macroporous WO3 particles with deposited Pt (Pt/WO3) were successfully synthesized for the first time, using flame-assisted spray pyrolysis. Nanoparticle aggregates-like structures (nanoaggregates) were formed, although a salt precursor was used for the synthesis. The macroporous structure was tailored by changing the mass ratio of the polystyrene template to ammonium tungstate pentahydrate. The cavities between the nanoaggregates formed mesopores, which increased the surface area. The presence of meso- and macro-pores in the synthesized Pt/WO3 particles improved their photocatalytic activities in visible-light-induced photodegradation of rhodamine B. The combination of a high surface area and the presence of an in situ-deposited Pt cocatalyst gave a high photodecomposition rate, approximately 9.6 times higher than that achieved with dense WO3 particles. This research provides a promising strategy for synthesizing submicron particles with high surface areas at a high production rate, and is suitable for industrial applications. (c) 2016 American Institute of Chemical Engineers AIChE J, 62: 3864-3873, 2016