This Letter reported reduction effect of pore wall on AuCl4- ions at low temperature (<100 C) and formation of Au nanowires within pores of monolithic mesoporous silica. Such nanostructured Au/silica assembly was obtained by soaking the silica into HAuCl4 solution, drying and annealing at less than or equal to 300 degreesC, without any special reduction treatment. Further experiments, revealed that the reducing groups OH. on pore walls are responsible for reduction of Au3+ ions at low temperature. The formation of Au nanowires can be attributed to the low nucleation rate, uni-directional diffusion of Au atoms along pore channels and the size confinement of pore channels. (C) 2003 Elsevier B.V. All rights reserved.