Ignition timing is heavily related to flame speed, which has great effect on SI engines performance. Due to that the flame speed for the fuel mixture that was formed by adding hydrogen to the traditional fuel was greatly changed, the ignition timing should be changed to attain suitable performance of the engine when used this mixture of fuels. The following experiments were performed to investigate the effect of ignition timing for different hydrogen percentages which mixed with gasoline fuel on a single-cylinder engine, four strokes. The tested hydrogen percentages by volume were 24%, 28%, 29%, 31%, and 49%. The analysis for engine performance was carried out at ignition timing positions (30 degrees, 35 degrees, 40 degrees BTDC). The results indicated that when the ignition timing was closer to top dead center (TDC) i.e at 30 degrees BTDC, the fuel consumption decreases and thermal engine efficiency increases. It is also noted that HC% increases and CO% were increased when spark time was more advanced for the same hydrogen concentration i.e at 40 degrees BTDC. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.