The desulfurization performance of the UDS solvents was investigated at an industrial side-stream plant and was compared with that of MDEA solvent. A mass transfer performance model was employed for explaining the COS absorp-tion into different solvents. Meanwhile, the regeneration performance of the UDS solvents was evaluated in side-stream tests. Results indicate that under the conditions covering an absorption temperature of 40℃, a pressure of 8.0 MPa, and a gas to liquid volume ratio (V/L) of around 230, the H2S content in puriifed gas can be reduced to 4.2 mg/m3 and 0 by using solvents UDS-II and UDS-III, respectively. Moreover, the total sulfur content in both puriifed gases is less than 80 mg/m3. As a result, the UDS-III solvent shows by 30 percentage points higher in COS removal efifciency than MDEA. In addition, the total volume mass transfer coefifcient of UDS solvent is found to be twice higher than that of MDEA. Furthermore, the UDS solvents exhibit satisfactory thermal stability and regeneration performance.