Thin films of ZnxCdl-xS were grown by ion-beam deposition on glass substrates. ZnxCdl-xS films with the c axis aligned perpendicular to the substrate and with high transmittance were obtained at a low substrate temperature of 70 degrees C. Although the properties of ZnxCdl-xS films greatly depend on substrate temperature and the composition parameter x, the optical bandgap and resistivity of the films are expressed systematically as a function of the film’s composition parameter x(f), which is determined by the (002) lattice constant following Vegard’s law. The optical bandgap of ZnxCdl-xS films varies from 2.42eV for CdS to 3.60eV for ZnS at substrate temperatures of 70-350 degrees C with x(f). The resistivity of films doped with indium varies from 10(-2) to 10(2) Omega cm with x(f) values of 0-0.4.