An experimental campaign was conducted for monitoring the formation of hydrocarbon gaseous compounds during bioleaching of copper sulphide ores with mesophilic microorganisms. Three different mineral samples were used: a pyrite concentrate, a chalcopyrite concentrate and a copper sulphide ore rock from El Teniente mine containing 1 % copper. Mineral samples were bioleached in 250 ml shake flasks containing 100 ml of basal medium inoculated either with a pure strain of Acidithiobacillus ferrooxidans or a natural bacteria consortium obtained from the acid leaching of El Teniente ore in columns. Each sealed system shake flask was fed with a flow of synthetic air and the exit stream was passed through a column containing an adsorbent material and next through a water trap as to avoid back air contamination from the environment. Compounds present in the adsorbent material after 90 days of bioleaching were analysed using a gas chromatography mass spectrometry technique with a procedure that detects 162 different hydrocarbon gaseous compounds (SGH). Results showed that the bacterial communities in copper sulphide bioleaching results in the formation of some hydrocarbon gaseous compounds, mainly various types of methyl benzene and branched alkanes. The formation of these organic compounds is likely to be related to the presence of heterothrofic microorganisms present in the natural populations.