GCB Bioenergy Published by John Wiley & Sons Ltd. Biochar–bioenergy coproduction from biomass pyrolysis has the potential to contribute to climate change mitigation. Biochar produced at various pyrolysis temperatures (<600°C) has been widely studied. However, the effect of biochars, produced at high pyrolysis temperature (≥600°C), on soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emission is largely unknown. A pot trial was performed to examine the effect of high pyrolysis temperature (600, 700, 850 and 950°C) woody biochars on soil N dynamics, microbial gene abundance and N 2 O emissions with (+N) and without N (−N) fertilization from an acid soil. Results showed that all biochar treatments significantly lowered the N 2 O emissions in both fertilized and unfertilized regimes. However, the suppressive effect on N 2 O emission among different high pyrolysis temperatures was not statistically different. Biochar amendment significantly decreased the concentration of soil NH 4+ , and lower levels of soil NO 3− were observed at the later stage of experiment. Under −N, plant biomass and N uptake were significantly lowered in all biochar treatments. Under +N, biochar addition significantly increased plant biomass, while only the 700°C biochar significantly increased N uptake. This suggests that single application of biochar could limit soil mineral N bioavailability and further decrease plant growth and N uptake in the plant–soil system. Biochar amendments tended to increase nitrous oxide reductase (nosZ) gene abundance, but this effect was only significant for biochar produced at 950°C under +N. In conclusion, high pyrolysis temperature biochars can be effectively used to reduce N 2 O emission, while increases in nosZ gene abundance and decreases in NH 4+ and NO 3− concentrations in the acid soil are likely to be responsible for the reduction in N 2 O emission. Thus, woody biochars as a by-product produced at high pyrolysis temperature have the potential to mitigate soil N 2 O emission via modifying N transformation and further affect climate change.