Nanoparticulate Ta3N5 was prepared by nitridation of nanoparticulate Ta2O5 precursor in an attempt to improve the photocatalytic activity for H-2 evolution from aqueous methanol solution under visible light (lambda > 420 nm). When platinum (Pt) was deposited in situ as a H-2 evolution cocatalyst, the as-prepared Ta3N5 with a primary particle size of 30-50 nm exhibited enhanced activity, three times higher than that of bulk Ta3N5 particles 300-500 nm in size. The improvement in activity arises from a lower density of defect sites, which is favorable for electron migration from the Ta3N5 bulk to the surface and/or for electron transfer from the conduction band of Ta3N5 to the loaded Pt. (C) 2009 Elsevier B.V. All rights reserved.