Hydrophobic CaCO3 particles were directly prepared via carbonation of Ca(OH)(2) slurry in the presence of sodium oleate at room temperature. Sodium oleate was used to modify the surface property of CaCO3 particles. The measurement of relative contact angle and active ratio indicated that CaCO3 samples were hydrophobic. DTG, FT-IR and TEM analysis of the obtained product indicated that the hydrophobic property was attributed to the deposition of calcium oleate, produced in the reaction mixture, onto the surface of calcium carbonate particles. They were covered on the CaCO3 crystals surface and modified their surface property; at the same time they own C=C bonds and could be polymerized or copolymerized later to give a polymeric monolayer. (c) 2006 Elsevier B.V. All rights reserved.