Abstract Cd(S,Se) thin films were successfully synthesized on the glass substrates via the CBD method followed by selenization. Cd(S,Se) compounds were formed when the selenization temperature exceeded 325°C. XRD analysis reveals that the prepared films had a cubic structure. The contents of selenium ions in Cd(S,Se) films were increased with increasing reaction temperatures and duration. The band gap of Cd(S,Se) films was controlled between 2.28–1.77eV by adjusting the selenium-ion contents. All of the synthesized films exhibited n-type characteristics, as determined from Hall effect measurement. The carrier concentration and the conductivity of CdS films were significantly promoted with the selenization process.