The study presented is devoted to the plasma steam-reforming of ethanol, methanol, ammonia, and vegetable oil. A particular attention is directed to the ability to use the plasma technology for the upgrading of the biomass products. A stationary discharge is used in order to perform physical diagnostics and also chemical analysis. The arc is formed between two electrodes made of graphite. The Gas Chromatography (GC) and Fourier Transform Infra Red (FTIR) techniques are used to determine the concentrations of various species (H2, CO, CO2, CH4 and C2) and to evaluate the efficiency of the process The effects of total flow rate of the inlet liquid mixtures and the nature of the reactants (alcohol, NH3, vegetable oil) on the produced species are studied.