Ignition delay times (IDTs) of fuel-rich CH4/dimethoxymethane (DMM)/air mixtures (phi = 2 and 10) were measured in a high-pressure shock tube at a pressure of 30 bar and compared to simulations based on reaction mechanisms for DMM from literature. Additionally, IDT of DMM/air mixtures were measured at similar conditions in a wide range of equivalence ratios (phi = 0.5, 1, and 2). Those mechanisms that predict the IDTs of DMM within the experimental uncertainties also predict the IDTs of the fuel-rich CH4 /DMM/air mixtures very well although they were not designed for these conditions. For the measurements at phi = 10, product gas samples were extracted from the shock tube test section at around 14-24 ms after arrival of the reflected shock wave by a fast-opening valve and analyzed with gas chromatography. Besides CO, H-2, and H2O, ethane, ethylene, acetylene, benzene, propene and toluene were observed as main reaction products. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.