As an approach to waste treatment and enemy utilization refuse derived fuels (RDF) have been developed as an alternative fuel for power generation. Combustion tests of RDF conducted in fluidized bed combustors and stokers have shown significantly different combustion characteristics and air pollution emission levels. To explain the differences from the view point of reaction mechanism of RDF, the combustion characteristics of a single RDF pellet (20 mm in diameter and 40 mm in length) made from municipal solid waste are investigated in an electric heating reactor (53 mm in inner diameter and 1.000 mm in length). The weight loss and the temperature profiles of the RDF pellet were measured under two groups of heating conditions: constant heating rate condition and instantaneous heating condition. It is found that the combustion of RDF progressed in two stages. In the first stage, volatile matters are decomposed and then burnt in Ras phase, and the weight loss rate of RDF significantly depends on the heating rate. The temperature difference between the surface and the inner RDF is small and thermal decomposition is the dominant process under smaller heating rate, However, considerable temperature difference between the surface and the inner is observed, and the heat transfer in RDF is the dominant process under the instantaneous heating condition. The ignition temperature of the RDF used in this work is around 480 degrees C. In the secund stage, fixed carbon is burnt in the solid phase, and the weight loss rate and the temperature profile in RDF are strongly affected by oxygen concentrations in the ambient lias. At higher oxygen concentrations, the heat of combustion is accumulated in RDF so that a high temperature peak is observed.