Structural and luminescent properties of CaS : Cu,F thin films prepared by the electron beam evaporation have been investigated. Both as-deposited and annealed films showed [110] orientation and the crystallinity of the film was improved with increasing annealing temperature. The films annealed at 700 and 750 degrees C in Ar and H2S showed strong blue emission spectra with peaks at 435 nm, whereas PL of the films annealed at 600 and 800 degrees C was broad band in visible region and poor intensity. It is suggested from the time-resolved emission spectra that the origin of blue luminescence not only from the powder phosphor but also from thin films is the intraionic transition in the Cu+ ion and not due to D-A pair recombination.