​The Azores archipelago is composed of nine volcanic islands located at the triple junction between the North American, Eurasian, and Nubian plates. Nowadays the volcanic activity in the archipelago is characterized by the presence of secondary manifestations of volcanism, such as hydrothermal fumaroles, thermal and cold CO₂-rich springs as well as soil diffuse degassing areas, and low magnitude seismicity. Soil CO₂ degassing (concentration and flux) surveys have been performed at Pico, Faial, and São Jorge islands to identify possible diffuse degassing structures. Since the settlement of the Azores in the fifteenth Century these three islands were affected by seven onshore volcanic eruptions and at least six destructive earthquakes. These islands are crossed by numerous active tectonic structures with dominant WNW-ESE direction, and less abundant conjugate NNW-SSE trending faults. A total of 2, 855 soil CO₂ concentration measurements have been carried out with values varying from 0 to 20.7 vol.%. Soil CO₂ flux measurements, using the accumulation chamber method, have also been performed at Pico and Faial islands in the summer of 2011 and values varied from absence of CO₂ to 339 g m^-2 d^-1. The highest CO₂ emissions were recorded at Faial Island and were associated with the Pedro Miguel graben faults, which seem to control the CO₂ diffuse degassing and were interpreted as the pathways for the CO₂ ascending from deep reservoirs to the surface. At São Jorge Island, four main degassing zones have been identified at the intersection of faults or associated to WNW-ESE tectonic structures. Four diffuse degassing structures were identified at Pico Island essentially where different faults intersect. Pico geomorphology is dominated by a 2, 351m high central volcano that presents several steam emissions at its summit. These emissions are located along a NW-SE fault and the highest measured soil CO₂ concentration reached 7.6 vol.% with a maximum temperature of 77°C. The diffuse degassing maps show that anomalous CO₂ degassing areas are controlled essentially by the tectonic structures and the lithology of the sites since the youngest volcanic systems are characterized by very low CO₂ emissions.