A comprehensive two-dimensional gas chromatography with time of flight mass spectrometer (GC x GC - TOFMS) was applied to analyze combustion products in exhaust gas emitted by a spark ignition combustion engine. N-heptane and toluene were used as fuel. For identification of detected compounds, NIST library search of the GC Image software was used. In exhaust gas of SI combustion using n-heptane as fuel, many types of branched chain compounds, aromatic compounds and naphthenic compounds were detected. On the other hand, in toluene SI combustion, most components of exhaust gas were aromatic compounds.