Recent works (e.g. Burton et al., 2013) synthesized the CO₂ released from volcanic/hydrothermal areas and highlighted the importance of accounting with these natural emissions to refine the global natural C-budget. The proposed project contributes to quantify the CO₂ emitted from quiescent volcanic areas, as it is the case of Terceira Island located in the Azores archipelago. In Terceira island of (~397 km²), Furnas do Enxofre is the only fumarolic field and it is located where the NW-SE periodically active basaltic fissure zone intersects the dormant volcanic structure of Pico Alto (Self, 1976). Results obtained will have a great impact on the knowledge of the degassing processes in an island where very little is known about the secondary manifestations of volcanism and integration of gas geochemical, structural and petrological data will also contribute to understand the origin of the released volatiles and can potentially be applied as an integrated methodology in other volcanic regions.