Nano-CaCO3 and nano-Al2O3 were modified using chloroform as solvent and fatty acid as modifier at room temperature. This modification process at room temperature can reduce energy consumption greatly. The results of Fourier transform infrared spectrometry (FT-IR) and transmission electron microscopy (TEM) demonstrated this modification process at room temperature was feasible. This new method for surface modification of nano-CaCO3 and nano-Al2O3 at room temperature has the potential to become a general method for surface modification of more nanoparticles. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.