AbstractAnionic polymerization of styrene in CSTR processes demands monomers which are highly pure. Lithium aluminum hydride (LAH) is a highly reactive material which reacts with the impurities in styrene that interfere with anionic polymerization. The LAH/impurity reaction products are not compatible with anionic polymerization and therefore must be isolated or removed from the styrene before polymerization. This problem is most readily solved by supporting the LAH on ion exchange resin beads such that the impurity reaction products are chemically bound to the support. We have demonstrated the preparation of>50 mol of polystyrene/mol ofn‐butyl lithium by passing the polymeization feed through a column filled with LAH/ion exchange resin. This represents>10‐fold improvement in yield (based onn‐butyl lithium) over previously described feed purification techn