The oxidation of CH4/diethyl ether mixtures was studied with laser absorption-based time-resolved temperature and CO concentration measurements behind reflected shock waves. Fuel-rich (equivalence ratio phi = 2.0) mixtures were studied because of their relevance for mechanism development for partial oxidation reactions in the context of polygeneration processes and measurements at phi = 0.5 and 1.0 were used to verify the mechanism performance in an extended range of equivalence ratios. Temperature and CO concentration were measured via absorption using two fundamental vibrations of CO (v '' = 0, P20 and v '' = 1, R21) with two mid-IR quantum-cascade lasers near 4.8546 and 4.5631 pm. Interference from broadband absorption of CO2 in the region near 4.56 pm was quantified based on measured temperature-dependent CO2 absorption cross-sections and mechanism-based prediction of CO2 concentrations. The measured temporal CO-concentration and temperature profiles were compared with simulations based on two mechanisms (Fikri et al., 2017; Yasunaga et al., 2010). For mixtures with phi = 0.5, the two mechanisms show similar results, and well reproduce the experimental data. At phi= 1.0 and 2.0, the Fikri et al. mechanism shows very good agreement with the experiments whereas the Yasunaga et al. mechanism predicts a too fast CO-concentration and temperature rise. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.