Luminescence, decay, and thermal quenching under photonic excitation of CaGa2S4:Eu2+ mono and polycrystals have been measured. For excitation into the lower 5d states, thermal quenching starts above 350 K, which makes this material appropriate for use as a yellow phosphor under excitation by blue-emitting diodes. Thermoluminescence after 337.1 nm irradiation is explained by photoionization of Eu2+ ions.