Biological nitrogen removal system is a significant source of nitrous oxide (N2O). The effect of temperature (10, 20, 25, 30, 35 degrees C) on the pollutant removal efficiencies and N2O emission characteristics of lab-scale A/O SBRs wastewater treatment process was evaluated. Results showed that temperature have no significant effect on the removal of COD while have a significant effect on the removal of nitrogen. During a certain range, as the temperature increasing the nitrogen removal rate increased. The nitrogen removal increased with the increase of temperature when it was below 25 degrees C and decreased with the increase of temperature when it was above 25 degrees C. Significant impact of temperature on the N2O emission was also observed. N2O emission decreased with the increase of temperature (N2O emission: 530.1, 260.8, 218.3, 104.7, 57.7 microg x g(-1)). For a lab-scale A/O SBRs treating wastewater, most of the N2O was produced during the aerobic phase, while no significant N2O emission can be detected during the oxide phase.