UV curable films were reinforced with an organically modified montmorillonite (MMT). The organically modified MMTs were prepared by an ion exchange process, in which sodium ions were replaced by alkyl ammonium ions. Cetyltrimethyl ammonium bromide (CTMA) modified clays gave rise to better intercalated clay morphology. The microstructurres were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Physical properties were examined by real time infrared spectroscopy (RTIR), differential scanning calorimetry (DSC), photo-DSC, dynamic mechanical thermal analysis (DMTA). Some tensile properties were also reported. Thermal and mechanical properties were generally improved with nanoclay reinforcements. The effects of nanoclays on the properties of UV curable films are critically evaluated in this paper. (C) 2004 Elsevier Ltd. All rights reserved.