Immobilized photocatalyst was prepared by the growth of ZnO nanograss on the ZnO pore-array substrate. The surface morphology, optical and photocatalytic properties of the photocatalysts were studied. Nanograss decorated ZnO pore-array films exhibited improved performance on the photocatalytic degradation of methyl orange (MO) in aqueous solution under UV radiation. The photocatalytic activity of pore-array films can be tuned by changing the surface nanostructure of the porous photocatalyst. The enhanced photocatalytic activity of the nanostructured pore-array photocatalyst can be attributed to increased active surface area, improved diffusion of dye molecules among the nanostructured catalyst, and enhanced light absorption through the light-trapping effect. Besides, the degradation of MO using Ag/ZnO composite pore-array catalysts with different sizes and densities of the Ag particles on the surface of ZnO nanostructure was investigated. (C) 2011 Elsevier B.V. All rights reserved.