Dimethyl ether (DME) is considered an alternative fuel for diesel engines with improved emission properties. The direct synthesis of DME from synthesis gas is a highly exothermic process. In this work, a microchannel reactor with improved heat and mass transfer has been used to produce DME from syngas. The experiments have been carried out in a wide range of reaction temperatures (210-300 degrees C), pressure (10-50 bar) and GHSV (4500-60,000 Nml/gcat/h), and the H-2:CO ratios of 1,2 and 4 have been applied. The temperature profile along the catalytic bed and an evaluation of the heat removal capacity of the reactor are investigated by a 2D pseudo-homogeneous dispersion model. The experiments and modelling results demonstrate that the DME production is conducted under practically isothermal conditions in the microchannel reactor. (C) 2010 Elsevier B.V. All rights reserved.