The rate of sulfur transfer across the gas/solid interface involving H2S(g) and alpha-Ag2+xS surface has been investigated using resistance relaxation measurements at 300 degrees C. The rate of the oxidation reaction incorporating sulfur into Ag2+xS has been found to decrease with sulfur activity in the sample as (alpha(S))-1/2 while the rate of the reduction reaction corresponding to the sulfur loss is found to increase with the sulfur activity as (alpha S)(1/2). The rate-limiting step has been identified to be H2S + 2e(-) = S2- (ad) + H-2