The absorption performance of low-partial-pressure H 2 S in a monoethanolamine (MEA)-activated Nmethyldiethanolamine (MDEA) aqueous solution was investigated. The absorption amount (in mass, g H 2 S/g solutions) and H 2 S loadings (mol H 2 S/(mol MEA + mol MDEA)) were measured, and the apparent absorption rate was determined from the time-dependent absorption capacity. Experimentally, the temperature and partial pressure of H 2 S (P H 2 S ) ranged from 303.2 to 323.2 K and from 300 to 500 Pa, respectively. The mass fractions of MDEA (w MDEA ) and MEA (w MEA ) ranged from 0.30 to 0.50 and from 0 to 0.075, respectively. The temperature, w MDEA , w MEA , and P H 2 S dependencies of the absorption performance were analyzed. It is impressive that the addition of MEA significantly enhanced the absorption amount of H 2 S yet slightly influenced the apparent absorption rate. In addition, a tray column consisting of six plates was used to verify the removal efficiency of low-partial-pressure H 2 S (P H 2 S = 500 Pa) and the results showed that in the case of w MDEA = 0.5, w MEA = 0.075, and T = 313.2 K, the removal efficiency achieved 95% when the ratio of gas to liquid was 40, indicating that MEA-activated MDEA aqueous solutions are promising in the removal process of low-partial-pressure H 2 S.