Epoxy - Clay Nanocomposites mate rials were successfully s ynthesized by an in - situ polym erization process . Epoxy resin D.E.R ™ 331 ™ and Tapanuli organoclay that were used as a matrix polymer and nanofiller, res pectively. The Influence of VersamidR 125 and Versamine® C31 curing agent on the mechanical and thermal properties of epoxy - Tapanuli organoclays nanocomposites were studied. The tensile strength using Versamine D31 shown tendency to decrease as the increasing of organoclay content. Otherwise, the increasing of organoclay content leads to the increasing of tensile strength on Versamid® 125 curing agent. It was due to the low viscocity of Versamine® D31. TEM observation show the intercalation and exfoliation structure for both of curing agent using. Their tensile modulus and heat deflection temperature increased with addition of Tapanuli clays composition below than 5 wt %. Morphology of epoxy - Tapanuli organoclay nanocomposites that was investigated using XRD and TEM showed the intercalated and exfoliated structures.