A versatile method for grafting reactive polymer onto macroporous polymer monoliths has been developed, and this method used to prepare a monolith containing primary amines. Reactive polymer was grafted onto residual olefins within the crosslinked monoliths using free-radical polymerization, and without requiring any pre-grafting activation. Capacities of the grafted monoliths were easily controlled by altering the composition of the grafting solution. Grafting N-vinylacetamide, followed by amide cleavage using hydrazine, afforded a monolith containing primary amine groups that was used for efficient continuous-flow scavenging of isocyanates, with 92% of phenyl isocyanate removed from solution in a reaction with a residence time of 49 min. High levels of scavenging required only a small excess of polymeric amine. (C) 2010 Elsevier Ltd. All rights reserved.