A magnetic composite of a meixnerite (Mg-Al-OH) type layered double hydroxide (LDH) and magnetite (Fe3O4), abbreviated as Fe3O4@(Mg-Al-OH LDH), was successfully synthesized by a mechanochemical route with a two-step milling operation. In the first step, the mixture of Mg(OH)(2), Al(OH)(3) and Fe3O4 as the starting materials was milled without water for 1 h, and then with addition water for another 5 h in the second step. The so-synthesized composite has the structure of Fe3O4 cores homogeneously dispersed in the LDH matrix and demonstrates super-paramagnetic behavior. This mechanochemical process provides a facile and environmentally safe method for synthesizing magnetic composites based on LDHs. (C) 2012 Elsevier B.V. All rights reserved.