The reaction mechanisms for dehydration of propylene glycol (1,2-propanediol) to propanone and propanal over the H-ZSM-5 and H-MOR catalysts have been theoretically studied using ONIOM(MO:MO) approach. The H-ZSM-5 and H-MOR catalysts modeled as 52T and 68T clusters were employed in the ONIOM(B3LYP/6-31+G(d):AM1) method. For the reaction either over the H-ZSM-5 or H-MOR catalysts, four steps for the propylene glycol conversion to propanone and three steps for the conversion to propanal were found. Thermodynamic properties, rate and equilibrium constants of these reactions are reported. (c) 2012 Elsevier B.V. All rights reserved.