The present work describes the design and application of 4-end spiral-wound modules, mainly for extraction applications. Membrane spacers, a key part of spiral-wound modules, are tested for pressure drop, mass transfer, and mixing behavior. Further, different permeate channel designs are studied by means of a transport-limited surface reaction (copper dissolution method). The findings led to the design of a 4-end spiral-wound membrane module with reduced propensity to dead zones and maldistribution and finally to its application to the reactive extraction of phenol.