A new cloud point extraction (CPE) method was created for extracting and concentrating thorium from a sulfuric acid leachate of rare earth elements (REESL). The method employs P,P′-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) as a chelating agent that has a strong attraction for actinides. By using Triton X-100 as a non-ionic surfactant and cetyl trimethyl ammonium bromide (CTAB) as an ionic surfactant, thorium is quantitatively extracted (over 98%) into a small volume of the surfactant-rich phase through heating and centrifugation. The method is based on in situ bromine formation to improve phase separation at highly acidic pH values resulting from the leaching steps. The method yielded a preconcentration factor of 22 when tested on REESL. To our knowledge, it is the first paper dealing with the use of CPE to selectively separate Th(IV) from rare earth elements and U from mining leachates.