In this study, waste palm shell was used to produce activated carbon (AC) using microwave radiation and zinc chloride as a chemical agent. The operating parameters of the preparation process were optimised by a combination of response surface methodology (RSM) and central composite design (CCD). The influence of the four major parameters, namely, microwave power, activation time, chemical impregnation ratio and particle size, on methylene blue (MB) adsorption capacity and AC yield were investigated. Based on the analysis of variance, microwave power and microwave radiation time were identified as the most influential factors for AC yield and MB adsorption capacity, respectively. The optimum preparation conditions are a microwave power of 1200 W an activation time of 15 min, a ZnCl2 impregnation ratio of 1.65 (g Zn/g precursor) and a particle size of 2 mm. The prepared AC under the optimised condition had a BET surface area (S-BET) of 1253.5 m(2)/g with a total pore volume (V-tot) of 0.83 cm(3)/g, which 56% of it was contributed to the micropore volume (V-mic). (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.