Post-combustion CO(2)capture is one strategy of greenhouse gases mitigation. Ammonia is a useful option as CO(2)absorbent and an alternative to conventional amine-based solutions. This study deals with CO(2)capture by ammonia aqueous solution in a co-current two-phase flow by utilizing a T-shaped microchannel. Three parameters of temperature, gas flow rate, and ammonia concentration were considered as the main parameters affecting the CO(2)capture efficiency. A response surface methodology based on central composite design (CCD) was used to model the CO(2)capture efficiency as output in terms of the aforementioned input variables. CCD suggested a quadratic model to fit the experimental data. The model validation was implemented by ANOVA. All statistic tools including correlation coefficient,P-value, and F-value of the model, andP-value of lack-of-fit confirmed that the prediction model was significant. It was deduced from F-values that the importance of the input variables followed the sequence of ammonia concentration > gas flow rate > temperature. Ammonia concentration was the most effective input variable because there was a direct correlation between ammonia concentration and the number of absorption sites in the liquid phase. Numerical optimization predicted the best output of 96.48% CO(2)capture under the following optimum conditions: temperature of 20.00 degrees C, gas flow rate of 110.59 mL/min, and ammonia concentration of 0.1382 mL/mL (13.82 vol%). The average CO(2)capture of 95.42% obtained at the input conditions indicates the accuracy of the prediction model.