Simultaneous removal of S02 and NOx using a regenerable solid sorbent will constitute an important improvement over the use of separate processes for the removal of these two pollutants from stack gases and possibly eliminate several shortcomings of the individual S02 and NOx removal operations. Recent studies at PHC considered cerium oxide as an alternate adsorbent to CuO. The present study aims to determine the effects of ammonia on the sulfation of the sorbent and to obtain a rate expression for the regeneration of alumina-supported CeOz sorbents. In the past quarter the effect of fly-ash, ammonia, and water on the sulfation of the sorbent was investigated. The analysis of the economics of a commercial scale ceria process has been sub-contracted to TECOGEN. This work has been completed and the report has been received.