Power generation in India is primarily coal-based in the present scenario. About 70% electricity generation produced by combustion of pulverized coal in thermal power plants. The available Indian coal quality is very poor; generate the large quantities of ash produced as by-products of combustion. The objective of the present study was to reduce the ash content and to produce ultra-clean coal. The coal sample was treated with chemical treatment of NaOH followed by HCl. The effect of particle size, temperature, and concentration on ash content was studied and found to be significant. Experimental influence parameters were optimized using Taguchi method. The result indicates that the temperature contributes the most dominant factor followed by acid concentration and particle size. The maximum reduction in ash content was observed at, particle size range of 53-75 mu m, temperature 70 degrees C, and concentration of NaOH 40% (by volume), respectively. After chemical leaching, the ash content was reduced from 35.33% to 0.65% so as to produce ultra-clean coal.