Solving a two-dimensional LTE (Local Thermodynamic Equilibrium) code, simulation of Ar-CO2 and Ar-N-2 PMITP (Pulse Modulated Induction Thermal Plasma) has been carried out. The active plasma power, fundamental frequency and gas flow rate are 27 kW, 0.45 MHz and 100/102.5 slpm, respectively. It has, been found that,the injection of excess dissociative molecular gases, shrinks the plasma and slows down the plasma response at the instant of off-to-on-pulsing transition, which results mainly from the molecular dissociation and ionization. Plasma response has been found faster at higher SCL (Shimmer Current Level) for the same duty factor during the on pulsing transition, and hardly affected by SCL and molecular gas addition during off pulsing transition. Pressure does not appreciably affect the response of Ar-CO2 plasma, whereas response of Ar-N-2 plasma becomes a bit faster at increased pressure. Part of the simulated results is compared with the corresponding experimental results. The agreement is found in some cases, and the remaining discrepancies between the results are critically evaluated with regard to various possible reasons. (C) 2003 Elsevier Science B.V. All rights reserved.