A study was made of the oxygen content in matters containing 0 to 20% Cu at 1523 K and at controlled oxygen and sulfur partial pressures. It was found that an increase in the sulfur partial pressure from 10**2 to 10**3 Pa at constant oxygen pressure leads to a sharp decrease in the oxygen content in the matter. A further increase in the sulfur pressure has practically no effect on the oxygen content in the melt.