Sulfur dioxide is one of the main intermediate compounds formed in the Claus process reaction furnace. In this work the possible reactions of this compound with other species were investigated thermodynamically over the operating temperature of Claus reaction furnace (800-1500 K). Through the study, the equilibrium composition of sulfur dioxide and compounds such as methane, carbon monoxide, carbonyl sulfide, carbon disulfide, hydrogen and hydrogen sulfide was calculated. According to literature, different pathways are possible for the reaction of SO₂ with some compounds such as methane. An attempt was made to find the most probable pathways. Competition of different compounds to react with sulfur dioxide was studied and it was found that the affinity of carbon disulfide, hydrogen sulfide and methane to react with sulfur dioxide is more compared to the other compounds.