Some approaches have been carried out for the degradation of organophosphorus pesticides using simple metal oxide nanostructures. This paper reports a comparison of the photocatalytic activity of ZnS and Ag2S with that of ternary semiconductor Zn0.5Ag0.5S nanocomposites without any surfactant for the degradation of the pesticides MLT, MCP, and CPS under UV light for environmental safety.