Alumina-supported cadmium sulfide photocatalysts for reduction of water to hydrogen were prepared by different techniques and characterized. The band gap, the dispersion of cadmium sulfide, and the contact between cadmium sulfide and alumina are affected by the preparation technique. Those preparation techniques that promote better dispersion of cadmium sulfide and give rise to a chemical interaction between cadmium sulfide and alumina impart a superior activity to the catalyst. The chemical interaction leads to decoration of cadmium sulfide surface by alumina which results in an intimate contact between them. Catalyst prepared by coprecipitation shows the intimate contact but has a poor dispersion of cadmium sulfide, whereas impregnation of alumina hydrogel results in a catalyst having both intimate contact between alumina and cadmium sulfide and better dispersion of cadmium sulfide; consequently, this results in enhanced activity.