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Experiments has been carried out on a hydraulically actuated rapid compression machine (RCM) under engine like condition using both pure methane and methane with 5 and 30 vol% hydrogen addition with a wide range of excess air ratios (1.0–2.2) for spark ignition (SI) mode. The RCM has a variable compression ratio, charge air preheating and control of cylinder block temperature, allowing both spark ignition and compression ignition without any modifications other than adjustments of the control system. Cylinder pressure and volume recordings were performed. The ignition and early combustion was visualized by a schlieren optical system and a high speed video camera at a rate of 10 000 frames per second. Flame size, and hence the apparent flame propagation velocity is found from the schlieren images, but the images are also used to investigate flame morphology for the different gas mixtures and excess air ratios studied.