Considering, the interfacial characteristics of goethite (alpha-FeOOH, iron oxide yellow), the in situ polymerization of methyl methacrylate was employed to modify the surfaces of alpha-FeOOH pigments in aqueous slurry. The scanning electron micrographs indicated that the poly(methyl methacrylate) anchored on the surfaces of the particle homogeneously. From this study, it was found that one of the key requirements in the synthesis of the alpha-FeOOH-PMMA composite was to enhance interfacial compatibility between inorganic particles and organic monomer. Moreover, polymer-treated alpha-FeOOH particles were easily dispersed in organic medium to form a stable colloid and the heat resistance of alpha-FeOOH particles was improved. (C) 2004 Elsevier Ltd. All rights reserved.