This paper presents PIC simulations of spark gap discharge, filled with Argon gas at atmospheric pressure. The rogowsky profile electrodes having an inter-electrode gap distance of 20mm were used in this study. The model is based on explosive electron emission from cathode, secondary emission and neutral Argon gas ionization. The phase space profiles, current density, ionization, temperature are presented. Results show that some simulations are in good agreement with existing experimental data. The simulation data of argon discharge was also compared with our previous work of nitrogen gas discharge. The difference between the two gases for using them as a dielectric medium in spark gaps is presented. © 2013 IEEE.