Thermosetting acrylic (TSA) resin was prepared by solution polymerisation of acrylic acid and methyl methacrylate (MMA). Hybrid polymer consisting of acrylic polyol-polyurethane was prepared by addition of hydroxy ethyl acrylate and hexamethylene diisocyanate (HMDI). Incorporation of Functionalised nanocalcium carbonate and bentonite nanoclay were accomplished by in situ method during the synthesis of both the polymers. Loading of nano-CaCO3 and nanoclay was varied from 0 to 4 wt.% to investigate variation in mechanical, optical and high performance properties. The superiority of nanoclay in enhancing the mechanical and performance properties like the salt spray and humidity resistance in comparison to that of nano-CaCO3 was clearly established. It was also observed that, addition of nanomaterials in hybrid resins system shows superior results compared to neat acrylic system and in situ additions of these nanomaterials improve the dispersion and stability in the matrix.