Grafting of chlorosulfuric acid on the amino-functionalized Fe3O4 nanoparticles afforded sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (SA-MNPs) as a novel organic-inorganic hybrid heterogeneous catalyst, which was characterized by XRD, FT-IR, TGA, TEM, and elemental analysis. The catalytic activity of SA-MNPs was probed through one-pot synthesis of a-amino nitrites via three-component couplings of aldehydes (or ketones), amines and trimethylsityl cyanide in water, at room temperature. The heterogeneous catalyst could be recovered easily and reused many times without significant loss of its catalytic activity. (c) 2011 Elsevier B.V. All rights reserved.