Copper gallium diselenide (CuGaSe 2 ) powders were synthesized via the sol–gel method followed by a selenization process. The sol–gel process can effectively reduce the required synthesis temperature to 400°C due to enhanced reactivity and improved composition homogeneity. The amount of Cu 2 Se impurity phase was decreased when sufficient Ga 3+ was added to the precursors. CuGaSe 2 powders were successfully prepared when the Ga 3+ /Cu 2+ molar ratio was increased to 2. The formation of CuGaSe 2 with a pure chalcopyrite structure was confirmed via the Rietveld refinement analysis. With decreasing Ga 3+ /Cu 2+ molar ratios, the particle size of the prepared CuGaSe 2 powders was significantly enlarged because the copper selenide phase acted as a flux for the particle growth. The optical absorption spectra revealed the obtained CuGaSe 2 to have a band gap of 1.68eV. The sol–gel method combined with the selenization process was demonstrated to provide a potential approach for fabricating CuGaSe 2 materials.