To investigate the mechanisms of nitrous oxide (N 2 O) emission during intermittent aeration in the composting process, a laboratory scale experiment with continuous measurement of N 2 O emission was conducted with cattle manure. A low oxygen mode (2.5% oxygen in the inlet for 1day), anaerobic mode (0.13% oxygen for 0.25day), and aerated mode (20.5% oxygen for 2days) were sequentially set up three times after 22days of continuous aeration to replicate intermittent aeration. The total N 2 O emission was 0.26–0.35mmol, 0.27–0.32mmol, and 0.14–0.23mmol during the low oxygen, anaerobic, and aerated modes, respectively. Denitrification was indicated as the main N 2 O emission pathway in the anaerobic and low-oxygen modes, while nitrification was indicated as the main pathway in the aerated mode and under continuous aeration. Results from this study suggest that nitrification is an important pathway for N 2 O emission as well as denitrification.