In recent years, an intense research effort has been focused on electrochemical cells for reduction of gases of nitrogen oxide radicals (NOx) due to the need to design an effective method for the purification of the exhaust gas from lean burn and diesel engines. A new type of solid-state electrochemical cell with composite Pt-YSZ cathode and nano-porous NiO-YSZ working electrode for decomposition of NO, gas in the presence of excess oxygen was proposed and investigated. It was shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nano-porous NiO-YSZ working electrode was linear and that the value of current efficiency is dependent on the NO and O-2 gas concentrations only. For the first time, an electrochemical cell for NO decomposition operating at do voltage lower than 1.7 V in the temperature range of 550-700 degreesC was designed. The combination of the new type of composite cathode with a nano-porous working electrode provides the possibility of large reductions in the electrical power required for NO decomposition in the presence of excess oxygen.