It is a major issue in the world that only one third of the total fuel input gets con-verted to work, whereas the remaining two thirds of the fuel input goes unused through the exhaust and cooling systems. In the present years, enormous research has been done for reducing the undesirable emissions in internal combustion engines. In this paper, using high velocity oxy fuel thermal spray method, ZrO2 and Al2O3 were coated over the piston head by fluctuating the important thermal spraying process parameters. A central composite design model was developed for conducting twenty different experiments with different spray process parameters. The coated piston was used in internal combustion engine to evaluate the emissions, which were measured using AVL5 exhaust gas analyzer to evaluate the smoke density and NOx content. Empirical relations were created between input process parameters with the responses. Analysis of variance was used to evaluate the significance of developed model. Response surface method-ology was used to optimize, thereby predicting the parameters of oxygen flow rate at 229 L/m, fuel flow rate at 51.2 L/m, spray distance of 194 mm to predict minimum smoke density of 27.7 HSU and NOx of 220.8 ppm, which was validated to a high level of accuracy.