A device for capture of acid gas of combustion fumes of a thermal power plant, including: absorption means (10) of the gas by capture fluid, a regenerator (1) where the capture fluid and a regeneration fluid steam are put in contact, introduction means (11) of the regeneration fluid in the regenerator, condensation means (2, 3, 4), at the head of said regenerator, separation means (6) of liquid phase of the regeneration fluid and gaseous phase rich in acid gas, Wherein: the regeneration fluid steam introduced is superheated, the regenerator (1) includes means limiting the contact time to substantially maintain the flow rate of regeneration fluid steam, the condensation means (2, 3, 4) are in thermal exchange with first evaporation means of working fluid, and first reintroduction means (13) of steam obtained in a turbine (14).