Calcium carbonate (CaCO3) particles were modified by a direct blending method using different coupling agents. The changes in the CaCO3 particles were determined using different techniques. Compared with pristine particles, the modified CaCO3 particles show good dispersion, particularly those modified by gamma-methacryloxypropyl trimethoxy silane. Results of the thermogravimetric analysis indicated that the coupling agents were adsorbed or anchored on the surface of the CaCO3 particles, thereby hindering aggregation. The formation of covalent bonds [Ca-O-Si] or [Ca-O-Ti] was verified using Fourier transform infrared spectroscopy and X-ray diffraction. The modified CaCO3 particles showed more stable colloidal dispersion in ethyl acetate than that of pristine CaCO3 particles. Some silane or titanate coupling agents can be combined with CaCO3 by covalent bonds, thereby changing the surface properties of CaCO3 and enhancing dispersion in many organic media. The hydroxyl groups on the surface of CaCO3 particles can interact with silanol groups or titanate coupling agents forming an organic coating layer. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.