Cu doped CdSe thin films have been successfully grown by vacuum evaporation technique at various substrate temperatures. XRD analysis revealed that the films exhibited hexagonal structure with (0 0 2) as the preferred orientation. The grain size of the films was varied by changing the deposition temperatures. The variation of grain size led to a change in the band gap of the films nonlinearly from 2.05 to 2.22 eV. The photoluminescence (Pt) spectral variation with effect of grain size and temperature was studied. In the PL spectra, the near band edge emission at 1.725 eV and the bound exciton emission at 2.132 eV due to nanocrystallites were observed at low temperature. SEM analysis showed that the grain size of the films was found to be large when the films were deposited at a substrate temperature of 100 degreesC, whereas films deposited at different temperatures exhibited nano size crystallites. The quantum confinement effect was observed as a function of grain size in the films. X-ray photoelectron spectroscopy was used to determine the composition, chemical state of the elements and the possible existence of secondary phases in the films.