In this research, oxidation of sulfide minerals and leaching of gold from a gold–bearing sulfide concentrate using chloride–hypochlorite solution was investigated. The effects of calcium hypochlorite concentration, sodium chloride concentration and initial pH of leachant on changes of the slurry pH and Eh were examined. Then, considering the stability range of the gold complex (Eh ~ 1000 mV) and for- mation of chlorine gas (pH < 3.5), the optimum leaching parameters were determined. The optimum conditions were obtained at 200 g/dm³ calcium hypochlorite, 200 g/dm³ sodium chloride and initial pH 11 (with 200 g/dm3 concentrate, stirring speed 600 rpm and temperature 25 C) at which about 82% gold was extracted in 2 h.