Taguchi technique and regression analysis have been used to find out the optimal operational parameters of pH value for coal water slurry in agitated vessel used in coal gasification power plant system. The pH values of coal slurry depends on the parameters of the experiment which include water/coal ratio, stirring speed, type of the stirrer, design of the vessel and conditions of the process. Experimentation is conducted in the agitated vessel and the signal-to-noise ratios are computed to determine the optimum parameters. The percentage contribution of each factor is validated by analysis of variance technique. Multiple regression analysis is conducted using statistical package with Minitab-15 software and the mathematical model is build to predict the pH value of coal water slurry for any given conditions. The regression analysis results are compared with experimental data and the average error was found to be 0.425%.