Solid solutions of CuInSe2-ZnSe have recently shown promising potential as a photovoltaic material. In this work we investigate the CuInSe2-ZnSe and CuGaSe2-ZnSe systems for high Voc photovoltaic applications. It was found that the highest Voc (∼740 mV) was achieved when the In/(In+Ga) ratio in the precursor was 0.13, i.e. very Ga-rich composition. Selenization conditions of CuZnGaIn metallic precursors were studied by changing reactive annealing parameters: temperature, dwelling time, temperature ramp and quantity of elemental Se. The optimal selenization parameters obtained in this study were: 550 °C, 30min, 20 °C/min and 50 mg of Se.