NO2　sensor　has　attracted　extensive　attention　due　to　its　important　application　in　environment　monitor.　Conventional　NO2　sensors　based　on　the　yttria-stabilized　zirconia　(YSZ)　electrolyte　possess　fast　response,　high　sensitivity　and　good　stability,　whereas　its　ionic　conductivity　decreases　significantly　at　low-　and　intermediate-temperature,　limiting　the　practical　application　in　motor　vehicles.　In　this　work,　a　pyrochlore-phase　A2B2O7　solid　electrolyte,　Pr2Zr2−xCexO7+δ　(PZC),　was　applied　for　the　first　time　to　construct　the　amperometric-type　NO2　sensor.　Ce　incorporated　significantly　improved　the　sensing　performance　of　the　PZC　NO2　sensor　with　NiO　as　the　sensing　electrode.　The　effect　of　Ce-doped　concentration　and　operating　temperature　on　the　sensitivity,　selectivity,　stability,　response　and　recovery　characteristics　were　investigated　in　detail.　The　results　showed　that　the　optimal　sensor　based　on　the　Pr2Zr1.9Ce0.1O7+δ　substrate　gave　high　sensitivity,　excellent　selectivity　and　quick　response-recovery　behavior　to　NO2　gas.　The　gas-sensing　mechanism　was　also　discussed.　The　PZC　sensors　are　well　established　effective　for　sensing　NO2　at　mild-temperature　working　window　of　500–700 °C,　and　thus　exhibit　the　promising　application　in　motor　vehicles.　©　2017　Elsevier　Ltd　and　Techna　Group　S.r.l.