► The present work provides field evidence on the effect of biochar on GHG fluxes in Mediterranean wheat crop. ► No significant increase of N 2O and CO 2 emissions observed in char treated plots. ► No significant effect of char on CH 4 soil consumption and production. ► Short term stimulating effect of biochar on soil microflora. Biochar has been recently proposed as a management strategy to improve crop productivity and global warming mitigation. However, the effect of such approach on soil greenhouse gas fluxes is highly uncertain and few data from field experiments are available. In a field trial, cultivated with wheat, biochar was added to the soil (3 or 6 kg m −2) in two growing seasons (2008/2009 and 2009/2010) so to monitor the effect of treatments on microbial parameters 3 months and 14 months after char addition. N 2O, CH 4 and CO 2 fluxes were measured in the field during the first year after char addition. Biochar incorporation into the soil increased soil pH (from 5.2 to 6.7) and the rates of net N mineralization, soil microbial respiration and denitrification activity in the first 3 months, but after 14 months treated and control plots did not differ significantly. No changes in total microbial biomass and net nitrification rate were observed. In char treated plots, soil N 2O fluxes were from 26% to 79% lower than N 2O fluxes in control plots, excluding four sampling dates after the last fertilization with urea, when N 2O emissions were higher in char treated plots. However, due to the high spatial variability, the observed differences were rarely significant. No significant differences of CH 4 fluxes and field soil respiration were observed among different treatments, with just few exceptions. Overall the char treatments showed a minimal impact on microbial parameters and GHG fluxes over the first 14 months after biochar incorporation.