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Tropical savanna ecosystems are a major contributor to global CO 2, CH 4 and N 2O greenhouse gas exchange. Savanna fire events represent large, discrete C emissions but the importance of ongoing soil-atmosphere gas exchange is less well understood. Seasonal rainfall and fire events are likely to impact upon savanna soil microbial processes involved in N 2O and CH 4 exchange. We measured soil CO 2, CH 4 and N 2O fluxes in savanna woodland (Eucalyptus tetrodonta/Eucalyptus miniata trees above sorghum grass) at Howard Springs, Australia over a 16 month period from October 2007 to January 2009 using manual chambers and a field-based gas chromatograph connected to automated chambers. The effect of fire on soil gas exchange was investigated through two controlled burns and protected unburnt areas. Fire is a frequent natural and management action in these savanna (every 1-2 years). There was no seasonal change and no fire effect upon soil N 2O exchange. Soil N 2O fluxes were very low, generally between -1.0 and 1.0μg Nm -2h -1, and often below the minimum detection limit. There was an increase in soil NH 4 + in the months after the 2008 fire event, but no change in soil NO 3 -. There was considerable nitrification in the early wet season but minimal nitrification at all other times. Savanna soil was generally a net CH 4 sink that equated to between -2.0 and -1.6kg CH 4ha -1y -1 with no clear seasonal pattern in response to changing soil moisture conditions. Irrigation in the dry season significantly reduced soil gas diffusion and as a consequence soil CH 4 uptake. There were short periods of soil CH 4 emission, up to 20μg Cm -2h -1, likely to have been caused by termite activity in, or beneath, automated chambers. Soil CO 2 fluxes showed a strong bimodal seasonal pattern, increasing fivefold from the dry into the wet season. Soil moisture showed a weak relationship with soil CH 4 fluxes, but a much stronger relationship with soil CO 2 fluxes, explaining up to 70% of