Microplasma discharge at relatively low voltages and very small discharge gaps is analyzed. The electrical characteristics of the microplasma electrodes and the small size of the supply circuit show that this technology can be applied for NOx removal processes especially for mobile exhaust gas sources. The effect of the discharge gas temperature and O2 amount in the gas composition are investigated. The electrode arrangement using a parallel connection allows the treatment of different gas composition at different flow rates. The experimental results show that with the increase of the discharge gas temperature the NOx removal efficiency increases for the gas composition without O2. At higher gas temperatures the energy efficiency of the NOx removal process is lower. By increasing the amount of O2 in the discharge gas the NOx removal efficiency will decrease. Due to the decomposition of O3 at higher temperatures with the increase of gas temperature the NO removal efficiency in the presence of O2 is decreasing and also fewer quantities of NO were oxidized to NO2. Higher NOx removal efficiencies were obtained at lower concentrations of NO and lower gas flow rates.