A study of the reductive regeneration of sulfated 4.3% CuO/Al2O3 catalyst-sorbents suitable for the simultaneous removal of SO2 and NOx from flue gases was carried out with various reductants. H-2 demonstrated a propensity to form CuS (ca. 20% CuS at 400 degrees C) and subsequent formation of H2S above 550 degrees C. Surface aluminum sulfate species are slowly reduced with Hz to the sulfide at temperatures in excess of 450 degrees C. Subsequently, H2S forms at higher temperatures, while bulk aluminum sulfate species were found to reduce in H-2 directly to Al2O3 with the formation of H2S above 550 degrees C. Although a much weaker reducing agent, regeneration with CH4 leads to significantly less CuS formation and no H2S production. The formation of CuS, which was not reduced by CH4, occurred via the readsorption of product SO2 gases on the catalyst-sorbent. Interestingly, no CuS was formed when water vapor was added to the CH4 reductant gases and more SO2 evolved in these conditions.