A new type of prickly nickel microwires assembled by thornlike nanocrystals was fabricated through a simple chemical reduction route with the assistance of citrate. Thus-prepared nickel wires were subsequently morphology-retained modified with a thin silver shell via transmetallation. Compared with the uncoated sample, the Ni-core-Ag-shell wires exhibited much-enhanced oxidation resistance, slightly changed magnetic properties and stark different catalysis for the creation of carbon particles in pyrolyzing acetone. (c) 2007 Elsevier Inc. All rights reserved.