The present paper describes the synthesis of N-arylacetamides through acetylation of arylamines with Ac2O in the presence of magnetically recyclable Fe3O4/Cu NPs. All reactions were carried out efficiently in H2O within 2–10 min to give the products in 89–95% yields. Selective acetylation of amines versus alcohols was carried out successfully with this acetylating system. In addition, acetylation of amines and phenols was taken place with the same reactivity. Reusability of the nanocatalyst was examined 5 times without significant loss of its catalytic activity.