The sulfide capacities of CaO-MgO-Al2O3-SiO2-CrO (x) slags were measured by gas-slag equilibration method in the temperature range of 1823 K to 1898 K (1550 A degrees C to 1625 A degrees C) to reveal the effect of CrO (x) on the sulfide capacities of slags. Both higher basicity and temperature enhanced sulfide capacities. The CrO (x) additions in the range of 0 to 5 mass pct increased the sulfide capacity, but, further increase of CrO (x) contents to 7 pct was found to lower the sulfide capacity. Utilizing the relationship for estimating the ratio of Cr(II)/Cr(III) put forward by the present authors, the influence of Cr(II) on the sulfide capacities of the slags studied is discussed.