The exfoliated natural rubber (NR)/organoclay nanocomposites were successfully prepared with an optimal organoclay by direction blending. The optimal-type organoclay was chosen by characterization of XRD and the mechanical properties characterization of the NR/organoclay composites from three kinds of organoclay. The observation of transmission electron microscopy (TEM) revealed well-ordered exfoliated single layers of organoclay. The results of mechanical properties measurement showed that the tensile strength, tensile modulus, and tear strength were improved remarkably with small amounts of organoclay, whose contents were below 5.0 phr. For example, incorporating with 3.0 phr organoclay, the tensile strength and tear strength of nanocomposite were 24.7 MPa and 34.7 kN/m, respectively, which increased similar to 89.5% and 61.6%. Furthermore, the results of coreinforcement system with high performance indicated a promising application of the organoclay and nanocomposites. The values of the weight-swelling ratio of nanocomposites decreased much, which meant the oil resistance of nanocomposites enhanced. The TGA results indicated that the thermal stability of nanocomposites was improved. The reduction of oxygen permeability implied the gas-barrier properties of the nanocomposites improved. Furthermore, the mechanism of barrier of clay layers was discussed. (C) 2008 Wiley Periodicals, Inc.