In the first application of eddy correlation in a hydrothermal region, we measured turbulent fluxes ranging between -17 and 13,500 g CO2 m-2 d-1 in Yellowstone National Park (YNP). These turbulent fluxes are similar in magnitude to chamber measurements of diffuse fluxes in the region. Negative turbulent fluxes due to vegetative uptake were measured in non-thermal regions. The flux footprint was used to compare turbulent with surface fluxes within the source area of EC measurements, and turbulent fluxes were consistent within error to the spatial extrapolation of chamber measurements. EC is more representative than chamber techniques, providing a viable alternative to measuring gas emissions in volcanic and hydrothermal terrain. ¿ 2000 American Geophysical Union