This article describes the synthesis of iron oxide nanocomposites from thermal decomposition of iron(III) acetylacetonate, in organic medium, in the presence of linear omega-functionalized polystyrenes. The nature of the magnetic particles was identified as magnetite (Fe3O4), based on X-ray powder diffraction and Raman spectroscopy, while the morphology and particle size of the so-prepared materials were evaluated by TEM technique. The resultant magnetic composites, with average particle sizes below 10 nm, can be easily dissolved in organic solvents, producing stable organosols. Magnetization measurements revealed that the nanocomposites exhibit superparamagnetic behavior at room temperature. (c) 2006 Wiley Periodicals, Inc.