Nanoporous-crystalline (delta and epsilon form) fibers of syndiotactic polystyrene (s-PS) have been prepared from melt-spun fibers by different guest-induced cocrystallization procedures. Their crystal structure, morphology, and uptake of volatile organic compounds (VOC) have been investigated. The use of chloroform, i.e., of a molecule being a suitable guest for both delta and epsilon forms but also a strong solvent for s-PS, leads to nanoporous-crystalline fibers with VOC sorption kinetics much faster than for s-PS nanoporous-crystalline powders and films and comparable with those of nanoporous-crystalline s-PS aerogels. This unexpected phenomenon is due to etching of the melt-spun fibers by chloroform that exposes internal fibrils and markedly increases the surface area up to 165 m(2)/g. Etched delta form fibers are more effective for sorption of most pollutants while etched e form fibers are much more effective in sorption of long organic molecules, like n-decane. Outstanding sorption properties, simple preparation processes (easily scalable at the industrial level), and safe morphology make etched nanoporous-crystalline s-PS fibers particularly suitable as sorption media for VOC removal from water and air.