There is growing interest in cofiring coal with industrial wastes, some of which have an elevated halogen content. This study looks at the effects of adding halogens in a CFBC system.: Experimental work was carried out on a pilot plant miniscale circulating FBC unit to which NaCl and I-2 were added during the combustion of a high-sulfur coke and a low-sulfur bituminous coal at typical FBC temperatures. Further, the effects of limestone addition and cofiring with natural gas in conjunction with halogen addition were also investigated. Results showed that the halogen species inhibited CO and suppressed NO reduction and N2O formation.:The distribution of halogen-containing products was predicted by the FACT thermodynamic database package for a wide range of combustion temperatures and other operating parameters. Results indicated that fuel type and combustion conditions have a pronounced effect bn the amount of halogen or halide released. Dramatic changes in halogen products and their distribution were produced by changing the fuel from coal to petroleum coke, by adding limestone, and by cofiring with natural,gas. A CFBC NO/N2O model has been employed which is based on the general kinetic model and a single particle NO/N2O formation model.; The model uses the semi-theoretical approach with some measured parameters as inputs. It is capable of describing the NO, N2O, and HCN concentration histories satisfactorily even in the case of iodine addition.