Thin films of ZnSe0.5CdS0.5 (t similar to 0.60 mm) were deposited at two substrate temperatures (350 and 470 K) by vacuum evaporation. The X-ray diffractograms (XRDs) indicated that the films were polycrystalline in nature with wurtzite structure irrespective of substrate temperature (T-s). The increase in lattice parameter with T-s could be due to better stoichiometry observed in the films formed at higher T-s. The refractive index of the films formed at higher T-s was generally higher. The refractive index and extinction coefficient were high at lower wavelength and this might be due to the free carrier absorption. The electrical conductivity and Hall measurements were carried out by de Van der Pauw technique. The temperature dependence of Hall mobilities shows that grain boundary scattering mechanism dominates and the grain boundary potential was found to be 0.055 eV in these films.