In this study, an experimental study on the performance of a spark ignition engine fuelled with CH4/ H-2 mixtures (90% CH4 + 10% H-2 and 80% CH4 + 20% H-2) was performed at different engine speed and different injection timing coefficient (ITC). This present work was carried out on a Lombardini engine. This is a four-stroke cycle two cylinder spark ignition engine with a bore x stroke of 72x62 mm and a compression ratio of 10.7:1. Experiments were made as 1200, 1600, 2000, 2400, 2800, 3200 and 3600 rpm and 100, 140, 160, 200 and 240 injection timing coefficients. In experiments, performance and emission parameters are investigated. For 90%CH4+10%H2 and 80% CH4+20% H-2, maximum brake thermal efficiency values are obtained 160 and 200 ITC at 2600 rpm, respectively. Minimum specific fuel consumption values are obtained 160 injection timing cefficient at the each mixture.