Pyrolysis of oil-palm (Elaeis guineensis Jacq.) shell, a cheap and abundantly available solid waste from palm oil producing process, was carried out using thermogravimetric analysis. The effects of raw material particle size and heating rate on the pyrolytic properties and kinetic parameters (activation energy, frequency factor and reaction order) were investigated. A one-step global model and a two-step consecutive reaction model were used to simulate the pyrolytic process and predict the weight loss during pyrolysis. The two-step model fitted the experimental data much better than the one-step model as the softening effect and formation of an intermediate during the pyrolytic process were taken into account. This two-stage reaction characteristic was confirmed by two obvious maxima in the derivative thermogram for pyrolysis of palm shells under different heating rates. The pyrolytic reactions at the low-and high-temperature regimes were found to be based on a first-order reaction mechanism and a contracting volume mechanism, respectively.