While CaS:Pb is already well known as an efficient UV/blue emitting photoluminescent phosphor, only preliminary results on its thin film electroluminescence are available. Thin film electroluminescent devices with a CaS:Pb active layer were deposited by electron beam evaporation. It was found that both the activator concentration and the substrate temperature during deposition strongly influence the optical characteristics. X-ray photoelectron spectroscopy was used to determine the composition of the layers, and the spectral characteristics were compared with results from photoluminescence.