Propanal (C2H5CHO) is a crucial intermediate oxygenated species in hydrocarbons and oxygenated fuels combustion, thus motivating a better understanding of its kinetics. In this study, two premixed at flames of propanal/hydrogen/oxygen/argon, a stoichiometric and a rich, are stabilized at low pressure (27 mbar) on a burner. Species mole fraction profiles have been measured by molecular beam mass spectrometry (MBMS) for the reactants, products, and intermediate species: C2H5CHO (propanal), H-2, O-2, Ar, H, OH, HO2, CO, CO2, H2O, CH3, CH4, CH2O (formaldehyde), CH2CO (ketene), CH3CO (acetyl radical), C2H2 (acetylene), C2H4 (ethylene), and C2H6 (ethane). The mechanism from the Universite catholique de Louvain (UCL) has been extended to the kinetics of propanal and its reliability has been validated against both of these propanal flames, at low pressure and in the temperature range up to 1530 K. According to the model, the main propanal consumption channel produces the ethyl radical (C2H5). This last radical is responsible for the hydrocarbons formation through C2H5 -> C2H4 -> C2H3 -> C2H2; and also for the oxygenated compounds production through C2H5 -> CH3CHO -> CH3CO -> CH2CO -> CH2CHO. The presence of hydrogen, as a reactant, promotes the propanal consumption with the H radicals.