Abstract: We report a means for efficient and selective extraction of carbon dioxide (CO2) at low to medium concentration from mixed gas streams. CO2 capture was accomplished by use of a novel enzyme-based, facilitated transport contained liquid membrane (EBCLM) reactor. The parametric studies we report explore both structural and operational parameters of this design. The structural parameters include carbonic anhydrase (CA) concentration, buffer concentration and pH, and liquid membrane thickness. The operational parameters are temperature, humidity of the inlet gas stream, and CO2 concentration in the feed stream. The data show that this system effectively captures CO2 over the range 400 ppm to at least 100,000 ppm, at or around ambient temperature and pressure. In a single pass across this homogeneous catalyst design, given a feed of 0.1% CO2, the selectivity of CO2 versus N2 is 1,090 : 1 and CO2 versus O2 is 790 :1. CO2 permeance is 4.71 × 10−8 molm−2 Pa−1 sec−1. The CLM design results in a system that is very stable even in the presence of dry feed and sweep gases.