The thermal behaviour, fire resistance and mechanical properties of jute-reinforced composites with vinylester and resol matrix were studied. Organically modified clay was added to the polymeric matrix in order to enhance the properties of the composites. An inhomogeneous distribution of the nanoreinforcement in the polymer was observed by X-ray diffraction. Thermogravimetric analyses revealed that the addition of clay to the resol resin by sonication enhanced the thermal resistance of the jute-reinforced composite at temperatures higher than 300 degrees C. The fire resistance of the composites was evaluated by means of a cone calorimeter. A diminution in the peak of the heat release rate was observed when clay was added to the polymeric matrix. On the other hand, neither the time to ignition nor the total heat evolved was significantly reduced by the clay addition. Additionally, an increment in the flexural modulus as well as in the flexural strength of the resol composites was observed when the clay was added to the matrix. The fiber-matrix interface of the composites was studied by scanning electron microscopy. It was observed that as the clay dispersion degree was increased the interface quality was diminished in the resol composites. (C) Koninklijke Brill NV, Leiden, 2010