Thermal spray coating process is an effective method to enhance the surface of the material. Detonation gun spray coating method (D-Spray) is one of the effective Thermal spray coating process. The material surface or substrate will be enhanced by deposition of coating powders such as metal oxides and ceramics like aluminium oxides, tungsten carbide, nickel chromium etc by D-spray method that prevents the metal from corrosion and to increase the wear resistance and microhardness. This coating process had wide applications in different engineering sectors such as aviation industry, marine industry, biomedical industry etc., In this Experimental study the optimization of Process parameter of D-spray coating process was done by Taguchi method in order to find the best processing conditions and to get higher quality of coating. Microhardness was estimated for various combinations of parameters and also the microhardness values has been predicted from the observation of interaction between fuel flow rate and coating thickness, powder flow rate and coating thickness, powder flow rate and fuel flow rate through RSM. An equation was derived to find out the micro hardness value for different input parameters of coating thickness(microns), powder flow rate(g/min), fuel flow rate (fmr) which gives the intermediate values of process parameters. © 2014 Published by Elsevier Ltd.