Woodblocks and rubber balls are used as the fuels to simulate the combustion behavior and pollutant emission characteristics of municipal solid wastes and hazardous wastes in a fluidized bed combustor with an intermittent feeding system. Silica sand is used as the bed material with a mean density of 2500 kg/m(3) and a particle size range of 400-500 mu m. Effects of operating parameters, i.e., in-bed stoichiometric oxygen ratio (ISOR), static bed height, and feeding interval on the CO and NOx emission concentrations are investigated. Different fuels show different pollutant emission characteristics in this study. For rubber ball combustion, the mean CO concentration in the flue gas increases with the ISOR and feeding interval and decreases with higher static bed height. There is a reverse dependency between the CO and NOx concentrations at the furnace exit. For woodblock combustion, the mean CO concentration decreases slightly with higher ISOR and static bed height and increases slightly with higher feeding interval. The dependency between CO and NOx concentrations is unobvious.