This paper provides a critical review on the applications of time-of-flight secondary ion mass spectrometry (ToF-SIMS) in heterogeneous catalysis, with a particular emphasis on the examples published during the last decade. The covered areas include supported metal oxide catalysts, supported metal catalysts, electrocatalysts for oxygen-reduction reaction and organometallic clusters as precursors for the preparation of heterogeneous catalysts. The molecular specificity and surface sensitivity of ToF-SIMS have been shown to be extremely useful in the surface characterization of heterogeneous catalysts, in particular in the areas of assessing the formation of new compounds or interactions between different components (e.g. active phase-active phase or active phase-support), providing more precision on the structure of surface species, monitoring the different steps of catalyst preparation and/or activation, etc. In some cases, ToF-SIMS is able to provide unique molecular information that is unattainable with other conventional techniques and thus give a more precise characterization of the heterogeneous catalysts. Finally, the advantages and limitations of ToF-SIMS with respect to other more conventional techniques such as XPS are also discussed. (c) 2013 Elsevier B.V. All rights reserved.