The dark and photocatalytic properties of Ni-doped WS{sub 2} supported on SiO{sub 2} were investigated. Adding Ni increases the dark catalytic hydrogen evolution activity of WS{sub 2}. With separate particles of CdS on SiO{sub 2} to photosensitize WS{sub 2}/SiO{sub 2}, the photocatalytic hydrogen evolution activity of Ni-doped WS{sub 2} maximizes at intermediate Ni loading levels. With fluorescein as a sensitizer, the addition of Ni lowers the activity of WS{sub 2}. The authors interpret the results in terms of a model in which Ni on the surface of WS{sub 2} plays an important role in controlling the surface geometric and electronic properties of the substrate and thereby the efficiency of interfacial energy and charge transfer.