Growing interest in environmental concern and vast industrial application makes Thorium popular and widely studies nowadays. In this study, solvent extraction process was done to determine the optimized parameters for the extraction of thorium. Parameters studied are the concentrations (M) of nitric acid (HNO3), percent (%) of Tri-Butyl Phosphate (TBP) in diluent and the volume ratio of acid to organic phase (VA:VO). The mixed rare earth (RE) oxalate powder was dissolved in HNO3 and Thorium elements was extracted using TBP diluted in kerosene. Energy dispersive x-ray fluorescence (ED-XRF) instrument was used to analyze the initial and final concentration of Thorium left in the aqueous solution. From the ED-XRF quantitative values, calculations were made to determine the extraction efficiency of Thorium. In the end of experiment, it is found that the optimized parameters are at 7M HNO3, 20% TBP diluted in kerosene and at VA:VO ratio of 2:3.