This study investigates single-event ignition of diesel fuel injected into air and into methane-air, the latter being applicable to compression ignition dual fuel engines. Diesel fuel was injected into the reflectionend of a 76 mm square-channel shock tube via a modern eight-orifice tip piezoelectric injector. Simultaneous schlieren and direct photography was used to characterize the ignition process and obtain a measure of the ignition delay time. Tests were carried out at a nominal reflected pressure of 10 bar and temperatures in the range of 880-1500 K. The test gas was composed of synthetic air, with argon replacing nitrogen. Diesel injection duration, e.g., 0.15 and 0.5 ms were tested, was found to have an effect on the ignition location and ignition delay time. A crossover in ignition delay time was observed at roughly 1100 K, which was attributed to evaporative cooling at higher temperature and fuel overmixing at lower temperatures. For the 0.15 ms diesel injection duration, ignition did not occur at temperatures below 1000 K due to overmixing. Premature ignition events caused by diaphragm metal particles were observed in the lower temperature range. When the premature ignition data was filtered out, the ignition delay time correlated well with an Arrhenius temperature dependency, except for temperatures below 1000 K where the ignition delay time became insensitive to temperature and showed significant data scatter. Experiments with diesel injection into methane-air resulted, in most cases, in mild ignition of the methane before diesel ignition. For temperatures above 1000-1100 K, detonation initiation of the methane-air occurred before diesel ignition. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.