Montmorillonite organoclay (MMO) was incorporated into epoxy resin by mechanical agitation and sonication process. Optical microscopy was used to analyse the optical homogeneity of dispersions. The properties of nanocomposite organic material were tensile strength, elongation at break and flexural strength. With 2 percent of MMO tensile strength and elongation at break could get optimum value. However, its strength values decreased when the weight percent of MMO increase to 3 percent. The flexural strength would be decreased with increasing the amount of nano clay in composite. The diffusion coefficient (D) could be calculated from the obtained data when dipping the composite sample in seawater and tap-water. They would be decreased with large amount of nanoclay in the sample.