Abstract Cds nanoparticles, prepared in a reverse micellar system, were immobilized directly onto alkanedithiol-modified Zn-doped silica particles, which were themselves prepared via hydrolysis of tetraethylorthosilicate in the presence of Zn(NO 3) 2 followed by contact with dithiol molecules. The resulting CdS–Zn–SiO 2 composite was then used as a photocatalyst for the generation of H 2 from 2-propanol aqueous solution. Under UV irradiation (λ>300 nm), a high photocatalytic activity was observed for the CdS–Zn–SiO 2 composite material. This is effected by electron transfer from the photoexcited ZnS (dithiol-bonded Zn on SiO 2) to CdS nanoparticles. The photocatalytic activity is increased with a decrease in the number of methylene groups in the dithiol molecules, according to the rank order 1,10-decanedithiol <1,6-hexanedithiol <1,2-ethanedithiol.