Conversion of methanol to light olefins (MTO) using acidic SAPO-34 molecular-sieve as the reaction catalyst was studied in a differential fixed bed reactor within the temperature range of 375-425 degrees C and under 4 bar pressure. The importance of MTO process is due to the increasing demand for light olefins in recent years. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The latter compound was then changed into protonated form by ion exchange method with ammonium chloride at 80 degrees C. A simple stoichiometric scheme has been presented for MTO. In addition a mechanism for this process based on Langmuir-Hinshelwood formulation has been put forward and the kinetic parameters have been evaluated as functions of temperature. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.