Catalytic CO oxidation over low-cost novel CoFeZnNiGa HEA nanoparticles, synthesized by cast-cum-crush method was carried out in the presence of the feed oxygen. The conversion and selectivity curves of CO oxidation at different GHSV indicate a maximum CO conversion of 99.8% was achieved at 175°C and 10,000 GHSV. Activation energy was found to be 3.8 kJ/mol, which is the lowest among the well-studied catalysts in the literature. Rates of the reaction at temperature 313k, 348k, 373k are found out to be 2.38, 5.26, 6.39 mol/g/sec, respectively. DFT calculations showed the high activity of Ni hollow sites for CO conversion where the ratedetermining step is the adsorption of CO having endothermicity of 1. % Conversion (X) of CO was calculated using the following equations :