Computational Fluid Dynamics (CFD) is used to investigate gas flow within spacer-filled channels in membrane modules for CO2 capture. The effects of spacer geometric parameters on velocity field and associated pressure drop are evaluated. The friction factor increases dramatically as the angle between filaments increases while the distance between filaments has little impact. A low pressure drop asymmetric spacer design is identified that has the potential to reduce pressure drop significantly. The influence of spacer geometry on membrane module performance is examined and the beneficial effects of reduced pressure drop on performance quantified.