Abstract: Nickel(II)oxide is a promising material which suits for many applications due to its speciality characters such as electrochromic, photocatalytic activity, semiconductor nature, etc. But use nickel oxide as filler in polymer composites is not well studied. In this work, nano nickel oxide filled vinyl ester matrix composites were fabricated by reinforcing various weight fractions of filler. The composites so prepared were characterized by mechanical strength analysis, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopic analysis. Outcome of the analysis showed that addition of nano NiO caused significant improvement in mechanical strength under tensile and bending stress and still further enhancement after the vinyl functionalization of nano nickel oxide.