The economical nanoclay/polymer nanocomposite with laudable thermal and barrier properties motivates scientists for its potential exploration in widespread engineering applications. The present investigation has been focused on the mechanical durability study of these nanocomposites at above ambient temperature environment. In-situ flexural testing was performed on epoxy based nanocomposites with 0, 0.5, 1 and 3 wt% nanoclay content at various temperatures (30, 50, 70 and 90 °C). Addition of only 0.5 wt% nanoclay in epoxy resulted in 17 and 26% improvement in flexural strength and modulus respectively (which is maximum among all the materials), when tested at room temperature, due to highest degree of exfoliation of nanoclay as confirmed from XRD analysis. At higher testing temperatures, all the materials exhibited a decreasing trend in their mechanical properties and a positive reinforcement effect was evident even up to the close vicinity of glass transition temperature. These findings were further verified by dynamic mechanical thermal analysis in a wide range of temperature varying continuously from 40 to 200 °C. The degree of dispersion and possible deformation and failure mechanisms were identified by scanning electron microscope.