Deactivation behavior is an important topic in catalyst development. In case of methanol synthesis the conventional Cu/ZnO/Al2O3 system is commonly known to be prone to sintering, however, information about the structural development during deactivation or the sintering mechanism(s) are scarce. We present a systematic deactivation study on three different Cu/ZnO/Al2O3 catalysts which are aged under constant conditions and periodically analyzed using kinetic measurements and N2O chemisorption. A power law model for the catalyst activity with time on stream is derived. Furthermore it is found, that the presence of water provokes a steep loss in active surface area and specific activity. Also, the TEM particle size distributions generated during the aging treatment are evaluated and discussed. (C) 2015 Elsevier B.V. All rights reserved.