In this study, the Response Surface Methodology (RSM) was applied for optimizing the extraction process of Naphthalene from its mixture with Base Oil and Dibenzothiophene using the ionic liquid 1-Butyl-3-Methyimidazolium Dimethylphosphate (BMIMDMP). The series of experiments conducted were designed using Design Expert version 8.7.0.1 software for studying the effect of temperature and ionic liquid to oil mass ratio on the performance of naphthalene removal. The Analysis of Variance (ANOVA) conducted to determine the relationship developed for the two variables above with respect to the naphthalene removal showed a high coefficient of determination (R2) value of (0.9998) hence indicating a very good performance model which can be used for optimizing the extraction process. Based on the results, it shows that 67 percent removal could be achieved with one extraction stage at the optimum condition. © 2014 Trans Tech Publications, Switzerland.