In this work, an experimental plasma-chemical reactor equipped with a water vapor plasma torch was used for catalyst-free thermal plasma reforming of propane to produce a synthesis gas. Thermal arc discharge plasma (a mixture of water vapor and argon) was generated at atmospheric pressure. The influences of the H2O vapor and C3H8 flow rates on the syngas production, composition, and energy conversion efficiency as well as specific energy requirements were investigated. The best results were obtained under the experimental conditions of H2O vapor flow rate of 360 l/min, C3H8 flow rate of 47 l/min, and input plasma torch power of 63 kW. The concentrations of the products were as follows: H-2 68.9%, CO 21%, CO2 5%, CH4 0.55%, and C2H2 0.9%. The C3H8 conversion ratio, H-2 yield, H-2 selectivity, and CO selectivity were 100%, 67%, 48.5%, 25.3%, respectively. The highest energy efficiency and the lowest specific energy requirement were 65% and 32.7 kJ/mol, respectively, and the H-2/CO ratio was 3.28. The modeling of chemical processes, based on the classical thermodynamic equilibrium reactor, was also proposed. The calculated data fit quite well the experimental results. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.