Abstract: Nano zinc oxide (ZnO) is extensively used as a UV-blocking material and finds application as a UV-blocker in cosmetics, textiles and protective coatings. However, with varying sizes and morphologies in the nano scale length, the UV-blocking behavior of nanoZnO gets varied. In the present study a DGEBA based epoxy coating on MS substrate was formulated and modified with nanoZnO with two different sizes and morphologies. Flake-like and spherical nanoZnO were synthesized by chemical routes using different precursors and characterized for their structure, size and shape. The nanoZnO modified epoxy coatings were exposed in UVB weathering conditions and the UV-blocking efficiency of the two types of nanoZnO particles were studied by evaluating the color change (dE) and yellowness index (YI) for the UVB exposed epoxy coatings with and without nanoZnO. It was observed that the flake-like nanoZnO was more efficient in lowering yellowing resistance of the epoxy coating on weathering compared to the spherical nanoZnO particles.