Poly(ether ether ketone) (PEEK) hollow fiber membrane modules were scaled up from 2 in. diameter and 16 in. long to 4 in. diameter and 58 in. long (a factor of 90 increase in membrane area) for CO2 capture from flue gases using a membrane contactor process, which combines advantageous features of both absorption and membrane processes. Field tests of a 4 -in.-diameter module with activated methyldiethanolamine (aMDEA) solvent demonstrated greater than 90% CO2 removal. The mass transfer coefficient in the absorption step was 1.2 (s)(-1), which is over an order of magnitude greater than that of conventional column contactors. The membrane module was further scaled up from 4 in. to 8 in. diameter (a factor of 3 increase in membrane area). Single-gas permeation measurements indicated that 8 -in. modules have an intrinsic CO2 permeance as high as 2150-2670 GPU. One 8-in.-diameter module was tested in membrane contactor mode for CO2 capture using a simulated flue gas. Carbon dioxide removal rate of 91.3% was achieved with a mass transfer coefficient of 1.5 (s)(-1). Parametric tests indicated CO2 flux and capture rate increased with increasing feed pressure, solvent flow velocity and solvent temperature. PEEK hollow fiber membrane contactor is effective in capturing CO2 from low CO2-concentration feeds, showing its high potential for coal or natural gas flue gas CO2 capture.