Benzimidazole derivatives were synthesized in good yield from 1,2-phenylenediamine (PD) and various alcohols by photocatalytic cyclization with TiO2/acidic clay composite catalyst using UV-A and solar light. Doping silver on TiO2 enhances product yield and selectivity of the photocatalytic synthesis of benzimidazoles. The higher efficiency of nano-Ag-doped TiO2 in solar light makes this synthesis a green chemical process.