We synthesized a solid solution of Ca(Al_ x Ga_1 – x )_2S_4 activated with europium ions Eu^2+. The photoluminescence spectra and photoluminescence excitation spectra of the crystals at 300 K for x = 0.2 are measured. The dependence of the luminescence intensity on the temperature in the range of 10–300 K is investigated. Based on the experimental results, the redshift, the Stokes shift, the activation energy, and the lifetime of the Eu^2+ ions are determined.