Poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS))-based microgel is prepared for metal nanoparticle preparation of Co and Ni and then used in hydrolysis of NaBH4. The Co(II) ions from different anion-containing sources is used for loading of p(AMPS) and used in Co nanoparticle preparation. It is found that loading of Co(II) into p(AMPS) is in the order of Cl- > CH3COO- > NO3- as well as the formed corresponding particles. The porous p(AMPS) microgel is prepared and used in metal nanoparticle preparation and porous p(AMPS) can load more Co(II) than p(AMPS)-silica and bare p(AMPS). The Co nanoparticle-containing composites also give catalytic performances in that order. The activation energy for hydrolysis of NaBH4 by p(AMPS)-Co microgel composites is calculated as 29.80 kJ/mol, that is as low as Ru nanoparticle-containing bulk p(AMPS) hydrogels. It is further revealed that the microgels based on p(AMPS) are versatile, can be used repeatedly up to five times without any loss of catalytic activity (only about 3%) and with no loss in conversion. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.