Trace carbon dioxide (CO2) removal from an enclosed space was studied experimentally and theoretically in a hollow-fiber membrane contactor using monoethanolamine (MEA) solution. Changes in trace CO2 removal performance with liquid flow rate, gas flow rate, absorption temperature, and CO2 loading were investigated individually in an apparatus under well-defined and controlled experimental conditions. We developed a two-dimensional (2-D) mathematical model to predict and further analyze the experimental results. The modeling results agreed well with the experimental work. Liquid flow rate positively influences trace CO2 removal, but is not recommended for operation at a very high level. Increasing the gas flow rate improves CO2 absorption flux at the cost of reducing CO2 removal efficiency; the optimal gas flow rate for the trade-off between CO2 removal efficiency and absorption flux is presented. The optimal absorption temperatures change with liquid CO2 loading for trace CO2 removal. CO2 removal efficiency is a decreasing function of CO2 loading; the recommended CO2 loading of MEA solution is below 0.35 mol CO2/mol MEA. To predict the influence of membrane wetting on trace CO2 removal, we also propose a model that incorporates membrane wetting. The minimum breakthrough pressure are 0.38 and 0.0581 MPa for fresh membrane and old membrane, respectively. Membrane wetting significantly deteriorates trace CO2 membrane absorption performance, with CO2 removal efficiency decreasing suddenly once the membrane is wetted.