Carbon dioxide decomposition has been studied using ac glow discharge plasmas at atmospheric pressure. A tubular reactor with a metal rod inside a quartz tube was wrapped with aluminum foil. The reaction mixture was analyzed by using a mass spectrometer. No coke deposits or other side reactions were observed. A variety of parameters, such as different metals, CO2 concentrations, flow rate of the CO2 containing gas, frequency, and power were investigated. The effects of these parameters on CO2 conversion, reaction rates, and energy efficiency were examined. The initial excitation voltage to produce the plasma is independent of the metal identity on the surface of the rod and the flow rate of CO2 containing gas, but dependent on the CO2 concentration and ac frequency used. The maximum energy efficiency was obtained with relatively high CO2 concentration, high flow rate of CO2 containing gas, high frequency, as well as low input voltage at the expense of conversion.