Cobalt oxides supported on several types of carriers (silica, molecular sieves 5A and 13X, and gamma-Al2O3) were evaluated for the reduction of sulfur dioxide by methane to elemental sulfur. Results showed that gamma-Al2O3 is the most effective carrier and that, with a molar ratio of 2 to 1 of sulfur dioxide to methane in a feed gas, the sulfur yield reached a maximum value of 87.5% at a space velocity of 5000 h(-1) and a temperature of 840 degrees C. X-ray diffraction results revealed that mixtures of cobalt oxide and cobalt sulfide components were observed. The effects of temperature, space velocity, and molar ratio of sulfur dioxide to methane in the feed on the activity of the cobalt catalyst supported on gamma-Al2O3 were investigated. The effect of feed gas containing a hydrogen sulfide contaminant was also studied. A catalyst size-dependence study was performed to determine the influence of the internal diffusion.