In this paper, a simple and green route for in situ growth of Au shell or grown Au NPs attached on the graphene oxide-iron oxide nanocomposite (GO-Fe3O4) was established. After functionalized with amino groups, the GO-Fe3O4 nanocomposites can adsorb negatively charged Au nanoparticles (Au NPs) which acted as gold seeds. Then the HAuCl4 solution provides gold precursor with glucose serving as reducing reagent, whereby the crystal growth leads to the in situ growth of Au shell or grown Au NPs attached on the surface of GO-Fe3O4, and a highly efficient catalyst denoted as GO-Fe3O4-Au NPs(G) was obtained. The prepared nanocomposites were characterized and their catalytic activity was evaluated using the reduction of 4-nitrophenol (4-NP) as a model reaction. It shows that the GO-Fe3O4-Au NPs(G) possess high catalytic performance for reduction of 4-NP with conversion rate of 100% within 100 s. Furthermore, the new catalyst can be stored for more than one month, easily recovered and reused at least for ten cycles. Comparing with the nanocomposites without crystal growth, the formation of Au shell or Au NPs attachment on the support via in situ growth approach not only apparently improves catalytic activity, recyclability but also increases their stability. (C) 2013 Elsevier B.V. All rights reserved.