The gas-phase reaction of activation C-O bond of CH3OCH3 by Ti+ has been investigated using density functional theory (DFT) at the 6-311++G(3df,3pd)H6-311+G(d) level. The structures of all reactants, intermediates, transition structures and products of this reaction have been optimized and characterized at the quartet and doublet electronic states. Crossing points (CPs) are localized, and the possible spin inversion processes are discussed by means of the intrinsic reaction coordinate (IRC) approach. Finally, two competitive reaction pathways, including the CP, are proposed from the most stable reactants to the most thermodynamically stable products. (c) 2006 Elsevier B.V. All rights reserved.