The authors developed a two-dimensional one-temperature chemical non-equilibrium (1T-NCE) model of Ar-CO2-H-2 inductively coupled thermal plasmas (ICTP) to investigate the effect of pressure variation. The basic concept of one-temperature model is the assumption and treatment of the same energy conservation equation for electrons and heavy particles. The energy conservation equations consider reaction heat effects and energy transfer among the species produced as well as enthalpy flow resulting from diffusion. Assuming twenty two (22) different particles in this model and by solving mass conservation equations for each particle, considering diffusion, convection and net production terms resulting from hundred and ninety eight (198) chemical reactions, chemical non-equilibrium effects were taken into account Transport and thermodynamic properties of Ar-CO2-H-2 thermal plasmas were self-consistently calculated using the first-order approximation of the Chapman-Enskog method. Finally results obtained at atmospheric pressure (760 Tort) and at reduced pressure (500, 300 Torr) were compared with results from one-temperature chemical equilibrium (1T-CE) model. And of course, this comparison supported discussion of chemical non-equilibrium effects in the inductively coupled thermal plasmas (ICTP). (C) 2009 Elsevier B.V. All rights reserved.