In this study, the dynamic-mechanical properties of fumed silica and silane-treated reinforced epoxy nano-composites were examined; silane-treated specimens demonstrated greater glass transition temperature, modulus, and less moisture absorption. An epoxy composite has been studied under hydrothermal ageing in order to investigate the effect of treatment on dynamical mechanical thermal analysis. The nanocomposites were kept in seawater up to 600 h. The process was then modeled using response surface methodology based on central composite design (CCD). Three models were developed to predict the influence of wet aging parameters on the Tg, modulus, and damping. Accuracy of predicted results was analyzed by the analysis of variance method. The optimum values predicted by the RSM and CCD were 1 % wt treated fumed silica followed by aging at 60 A degrees C. Multiple correlation coefficients (R (2)) of 0.96 were obtained from the regression models for Tg, confirming the good accuracy of developed models.