Abstract: The capacity of CaO for binding HCl from incineration of organic wastewater which contains C₂H₃Cl₃O₂ was investigated at 500—800 ℃ in a bubbling fluidized bed.The binding capacity was the largest at 600 ℃, and then decreased with increasing temperature.Scanning electron microscope (SEM) analyses showed that the rate-limiting step for the reaction altered with the extent of solid conversion in sequence at temperature exceeding 600 ℃: chemical reaction control,and simultaneous chemical reaction and product layer diffusion control for a long period of time.There was not a single product layer diffusion control.The experimental results were analyzed by using the unreacted shrinking core model.The activation energy of product layer diffusion was about 9.95 kJ•mol^-1 for the range of temperatures in the fluidized bed.