The oxidation of propene in aqueous HCIO4, solution was studied on polycrystalline Au electrodes using differential electrochemical mass spectrometry (DEMS) and in-situ Fourier transform IR spectroscopy (FTIRS). Experimental results show that the interaction of propene with the electrodeelectrolyte interface is characterized by a weak adsorption since no chemisorbed intermediates could be found. Different reaction pathways were observed during the electro-oxidation of propene. Acetone was identified as the main product of the intact molecule chain. The detection of ethanal and carbon dioxide indicates fission of a C-C bond in a reaction pathway parallel to propene electro-oxidation.