[en] Electrolysis of solid chalcopyrite (CuFeS_2) against a graphite inert anode has been studied in equimolar NaCl-KCl melt at 700 °C. During electrolysis, S"2"− ions are released from the solid CuFeS_2 cathode, transfer to the graphite anode and discharge to S_2 gas. The reduction mechanism of CuFeS_2 was investigated by cyclic voltammetry, potentiostatic and constant voltage electrolysis together with spectroscopic and scanning electron microscopic analyses. The reduction contains mainly three stages: the insertion of Na"+ or K"+ into CuFeS_2, forming L_xCuFeS_2 (L = Na or K, x ≤ 1); the partial reduction of L_xCuFeS_2 to L_x_-_wCuFe_1_-_yS_2_-_z and Fe; the complete reduction to a mixture of Cu and Fe, which can be magnetically separated. After the separation, pure Cu can be obtained by leaching out the residual Fe with acid. Electrolysis at a cell voltage of 2.4 V has led to a rapid reduction of CuFeS_2. The current efficiency and energy consumption were 85% and 1.68 kWh/kg-CuFeS_2, respectively.