The photoluminescence and photoluminescence excitation spectra and luminescence decay kinetics of CaGa2S4:Eu2+ bulk crystals and powders ranging in particle size from 100 to 600 nm have been studied in the temperature range 77–300 K. The results indicate that the full width at half maximum of the photoluminescence band of the CaGa2S4:Eu2+ nanopowders is about twice that of the bulk crystals. Analysis of the photoluminescence spectra shows that the energy position of the emission band is almost independent of the particle size, temperature, and excitation intensity in the ranges 77–300 K and 10−3 to 106 W/cm2, respectively. The shape of the photoluminescence band is well represented by a Gaussian. The excited state lifetime of the Eu2+ ion is ∼1000 ns as evaluated from the exponential portion of the luminescence decay curve.