Ruthenium nanoparticles supported on non-cross-linked soluble polystyrene were prepared by reacting [RuCl(2)(C(6)H(5)CO(2)Et)](2) with polystyrene in open air. They effectively catalyze intra- and intermolecular carbenoid insertion into C-H and N-H bonds, alkene cyclopropanation, and ammonium ylide/[2,3]-sigmatropic rearrangement reactions. This supported ruthenium catalyst is much more reactive than [RuCl(2)(p-cymene)](2) and [Ru(Por)CO] for catalytic intermolecular carbenoid C-H bond insertion into saturated alkanes. By using alpha-diazoacetamide as a substrate for intramolecular carbenoid C-H insertion, the supported ruthenium catalyst can be recovered and reused for ten successive iterations without significant loss of activity.