Polyoxymethylene dimethyl ethers (OME) produced from methanol are considered as potential substitutes of Diesel fuel. Emissions of formaldehyde and other components have been observed, particularly under cold-start conditions in engine test-bench experiments with OME fuel. In this study, the reactivity of OME₃ (CH₃O(CH₂O)₃CH₃) and its decomposition products was studied in the temperature range 80–450 °C in a model gas test bench over V₂O₅/WO₃/TiO₂ and Cu-CHA SCR catalysts, a platinum-coated V₂O₅/WO₃/TiO₂ ammonia slip catalyst (ASC) and two diesel oxidation catalysts (DOC), based on platinum and platinum-palladium. Already at 80 °C, OME₃ was largely hydrolyzed to methanol and formaldehyde over all catalysts. At temperatures above 150 °C, V₂O₅/WO₃/TiO₂ oxidized methanol and formaldehyde to CO via formic acid as intermediate. The platinum ASC showed a similar behavior but oxidized the decomposition products to CO₂. Whereas Cu-CHA hydrolyzed OME₃ quantitatively to methanol and formaldehyde, it did not show oxidation activity in the studied temperature range. The data indicate that the release of significant amounts of OME from a catalytic converter can be virtually ruled out under cold start conditions, but also that low temperature hydrolysis produces formaldehyde and methanol emissions.