Cd1-xZnxS alloys were successfully deposited on indium-tin oxide (ITO)-coated glass substrates from an aqueous solution containing Cd2+, Zn2+ and S2O32- ions by photochemical deposition (PCD). The concentrations of Cd2+ and Zn2+ ions were varied to obtain the entire range of compositions from x = 0 to 1. Raman scattering studies were carried out for the as-deposited and annealed films. The alloy composition x was determined from the longitudinal optical phonon frequency observed from Raman spectroscopy. The composition of the alloy was also calculated by X-ray diffraction analysis and compared with the composition calculated from Raman spectra.