A kinetic study of the anaerobic digestion of palm oil mill effluent (POME) was carried out in a continuous, well-stirred digester with microorganisms immobilised on saponite support granules. A COD removal of 96.2% was achieved in the reactor at a volumetric loading rate of 10.6 kg COD/m3 day (hydraulic retention time of 6.2 days); the methane production rate was first order with respect to biodegradable substrate concentration. The apparent rate constant was proportional to the volatile suspended solids concentration and the product yield coefficient, Y(p), was 0.325 litre CH4 STP/g COD consumed.