Polymeric nanometer-thick membranes or nanomembranes possessing photocontrollable permeability are presented. Microcapsules are used as membrane model systems, while gold nanoparticle aggregates are used as active absorption centers. Upon laser light illumination the membranes change permeability reversibly because nanoparticles transiently affect the nearby polymeric network. Nanomembranes reseal to their impermeable state when the laser is switched off. This presents a novel and simple way of reversible permeability control of interest to intracellular signaling and membranes.