The ability of praseodymium doped cerium oxide materials to electrochemically reduce NO and O-2 was studied using cone-shaped electrodes in conjunction with cyclic voltammetry, in the temperature range 200-400 degrees C. Four samples were studied; Ce1-xPrxO2-delta (x = 0.1, 0.2, 0.3 and 0.4). It was shown that the current densities in both NO an O-2 gases increased with increasing praseodymium doping. Ce1-xPrxO2-delta had higher activity in an atmosphere containing NO than in an atmosphere containing O-2 in most cases and this trend was stronger at the lower temperatures. Ce0.8Pr0.2O2-delta and Ce0.9Pr0.1O2-delta seemed to have the highest ratio of maximum cathodic current density (i(NO)/i(O2)), which is used as an indication of a higher activity toward reduction of NO compared to reduction of O-2. The apparent selectivity generally decreased with increasing temperature for all the compositions. (C) 2013 Elsevier Ltd. All rights reserved.