Absorption of CO/sub 2/ and/or H/sub 2/S utilizing solutions containing two different activators

The removal of CO/sub 2/ and mixtures thereof with H/sub 2/S from gaseous mixture containing same, is carried out by using an absorbing solution which comprises a first activating substance chosen from aminoacids and primary and secondary ethanolamines, which effects the initial absorption of CO/sub 2/ with formation of a carbamate, a second activating substance chosen from As/sub 2/O/sub 3/ and its derivatives, secondary ethanolamines and ammonia, which promotes the hydrolysis and decomposition of the carbamate as the latter forms, and a third substance of a basic nature, which effects the quantitative absorption of CO/sub 2/ or CO/sub 2/+H/sub 2/S.