The aim of this paper is to present a comparison between a modified ignition system, based on a double spark plug, and a classical one in terms of the exhaust gases composition. The unburned hydrocarbons evacuated by a one-cylinder gasoline engine after the combustion was investigated using gas chromatography-mass spectrometry (GC-MS). A directly sampling method called solid phase microextraction (SPME) has been used to collect the organic molecules. The results obtained were also correlated with the values of the electrical energy supplied to the discharge.