The intrinsic kinetics of the three-phase dimethyl ether (DME) synthesis from syngas over a bi-functional catalyst has been investigated in a agitated slurry reactor at 20-50 bar, 200-240 degrees C and H-2/CO feed ratio from 1 to 2. The bi-functional catalyst was prepared by physical mixing of CuO/ZnO/Al2O3 as methanol synthesis catalyst and H-ZSM-5 as methanol dehydration catalyst.The three reactions including methanol synthesis from CO and H-2, methanol dehydration and water gas shift reaction were chosen as the independent reactions. A kinetic model for the combined methanol and DME synthesis based on a methanol synthesis model proposed by Graaf et al. [G.H. Graaf, E.J. Stamhuis, A.A.C.M. Beenackers, Kinetics of low pressure methanol synthesis, Chem. Eng. Sci. 43 (12) (1988) 3185; G.H. Graaf, E.J. Stamhuis, A.A.C.M. Beenackers, Kinetics of the three-phase methanol synthesis, Chem. Eng. Sci. 43 (8) (1988) 2161] and a methanol dehydration model by Bercic and Levec [G. Bercic. J. Levec, Intrinsic and global reaction rate of methanol dehydration over gamma-Al2O3 pellets, Ind. Eng. Chem. Res. 31 (1992) 399-434] has been fitted our experimental data. The obtained coefficients in equations follow the Arrhenius and the Van't Hoff relations. The calculated apparent activation energy of methanol synthesis reaction and methanol dehydration reaction are 115 kJ/mol and 82 kJ/mol, respectively. Also, the effects of different parameters on the reactor performance have been investigated based on the presented kinetic model. (C) 2008 Elsevier B.V. All rights reserved.