Polycrystalline Cd1−x Zn x S films were prepared by coating a slurry which consisted of CdS, CdCl2,, various amounts of ZnS and propylene glycol on to glass substrates and by sintering in a nitrogen atmosphere, and their sintering behaviours and electrical properties were investigated. As the amount of ZnS increases, the enhancing effects of CdCl22 on sintering and doping decrease, due primarily to the formation of ZnCl2 which evaporates rapidly during sintering, resulting in poor microstructure and a sharp increase in electrical resistivity. The sharp increase in the electrical resistivity is related to a sharp decrease in electron concentration which is caused by poor doping efficiency, and by an increase in the donor ionization energy of chlorine as the zinc content increases. The trap density of grain boundaries, on the other hand, decreases with increasing zinc content in sintered Cd1−x Zn x S films.[/p]