Template-free mesoporous silica SBA-15 was reacted with TPTAC to generate positively charged functional groups PTA + on the pore surface. Through ion exchange, a uniform distribution of anionic metal complexes on the intrachannel surface of host silica was achieved. In this study, ethanol and water were used as solvent for HAuCl 4 precursor solutions impregnated on SBA-15 mesoporous silica. The solvent used can affect the size and location of the resulting nanoparticles. Large Au nanoparticles (15–43 nm) were found on the as-prepared Au/SBA-15 as observed by PXRD, XAS, UV–vis and TEM. This may have originated through Si–OH reduction of chloroaurate complexes generated in the aqueous solution of HAuCl 4 , and such particles were not present when ethanolic solution was used. After NaBH 4 and H 2 reduction, the average size of Au nanoparticles, which was incorporated into the channels of SBA-15, was found to be limited to ≤ 7 nm.