Abstract Total CO 2 output from fumaroles, bubbling and water dissolved gases and soil gases was investigated at Pantelleria Island volcano, Italy. The preliminary results indicate an overall output of 0.39 Mt a −1 of CO 2 from the island. The main contribution to the total output was from diffuse soil degassing (about 0.32 Mt a −1), followed by dissolved CO 2 (0.034 Mt a −1), focussed soil degassing (0.028 Mt a −1) and bubbling CO 2 (0.013 Mt a −1). The contribution of CO 2 from fumarole gases was found to be negligible (1.4×10 −6 Mt a −1). Carbon-13 values for CO 2 coupled with those for associated He in gases from fumaroles and sites of focussed soil degassing clearly rule out any significant organic CO 2 component and suggest a common mantle origin for these gas species. The inferred mantle source beneath Pantelleria would seem to have peculiar geochemical characteristics, quite distinct from those of mantle producing MORB but compatible with those of magmatic sources of central Mediterranean and central European volcanoes. These findings indicate that the Pantelleria volcanic complex is a site of active mantle degassing that is worthy of attention for future geochemical surveillance of the island.