Many kinds of waste fuels such as municipal waste, waste plastics, refuse derived fuel (RDF) and so on were burned experimentally, using the test facility having a combustor of almost the same height and gas residence time as that of the industrial scaled CFBC. The objectives of these tests were, firstly to investigate the combustion characteristics of the waste fuels listed above, and secondly to grasp the formation and decomposition behavior of dioxins in the combustor, the cyclone, the convection part and the dust collector, in terms of the isomers of dioxins, respectively, in which the number of chlorine is different from one another. The test results indicate that, firstly adding Ca compounds such as CaCO3 or Ca(OH)(2) into the combustor is effective to prevent dioxins from forming: in the combustor, and secondly the activation energy of the dioxin decomposition is approximately 250 kJ/mol on average.