The feasibility of the reaction between a metal and a long-chain fatty acid (stearic acid or behenic acid) was studied systematically and comprehensively for the first time. It was found that metals of Mn, Fe, In, Zn, Ga, Sn, Co, Cd, Ni, Pb, Cr, Mo, Nb and Sb could react with molten stearic acid in decreasing rate of reaction to give metal stearates. The initiation temperature of the metal - fatty acid reaction was investigated and the resulted metal stearates were characterized by FT-IR, XPS and TGA. Nearly monodisperse iron oxide, manganese oxide and cobalt oxide nanoparticles could be generated by thermal decomposition of the as-synthesized metal stearates without any additional organic solvents. The size and shape control of the nanocrystals was achieved by simply varying the pyrolysis temperature and duration, and metal to acid ratio. (C) 2016 Elsevier B.V. All rights reserved.