there is disclosed a multi - stage process for reducing sulfur dioxide to sulfur or to hydrogen sulfide whereby a hydrogen - containing gas from a high temperature gasifier is used . in the first stage of the process , the gasifier exit gas is contacted at a minimum temperature of about 1800 ° f . with recycle gas containing so 2 , h 2 s , cos , mercaptans , and cs 2 in order primarily to reduce the organic sulfur compounds , i . e ., cos , mercaptans , and cs 2 , which heretofore would tend to accumulate in prior known methods employing a carbonaceous fuel for the reduction of so 2 . gas leaving the first stage is then sent to a second stage wherein so 2 from an external source is added . reduction of sulfur dioxide occurs in the second stage at a temperature of about 2000 ° f . minimum , with the surplus heat of reaction removed by the generation of steam . gas leaves the second stage and is thereafter cooled with simultaneous generation of steam and selective condensation of sulfur vapor . after cleaning and compression , the residual sulfur compounds contained in the gas may be removed and may then be returned to the first stage of the process or else introduced to a known sulfur recovery process . the disclosed process can permit the production of a useful gas without the need for preheating reactants or supplemental steam generation . in addition , the release of sulfur compounds to the atmosphere is eliminated or reduced in an economical manner . a minimal amount of process steam is used on an overall basis , thereby minimizing the problems associated in prior methods with condensation of sulfur vapor or treatment of aqueous effluents .