The present invention comprises a method of treating an off-gas stream from a refining process to remove sulfur compounds. A portion of the off-gas stream containing hydrogen sulfide is injected at the front end of the thermal reactor and in at least one other location downstream of the thermal reactor. A ratio of hydrogen sulfide to sulfur dioxide at the outlet of the thermal reactor is less than the stoichiometric requirement. The ratio is adjusted downstream of the thermal reactor so that a ratio of hydrogen sulfide to sulfur dioxide is maintained substantially in excess of the stoichiometric requirement for a Claus reaction. The tail gas, containing hydrogen sulfide but virtually no sulfur dioxide, is treated by a process including removal of water and introducing sulfur dioxide into the tail gas in a stoichiometricly balanced quantity and processing the tail gas in a Claus reactor.