Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid refractory samples. Thoria based mixed oxide nuclear fuels requires more than 1,200^oC reaction temperature to lose its structural integrity so as to release the halides. In the present paper, we report WO₃ accelerated pyrohydrolytic extraction technique for the separation of F^- and Cl^- from thoria based fuels along with the feasibility of using MoO₃ and V₂O₅. The mechanism of extraction has been investigated in detail using X-ray diffraction and recovery studies. ThO₂ along with its halides undergo high temperature solid state reaction with WO₃ forming Th(WO₄)₂ and releasing the halides for their subsequent hydrolysis. The quantification was carried out by ion chromatography with suppressed ion conductivity detection. The average recoveries of the spiked samples for F^- and Cl^- were 93–99%. The method was successfully applied for simultaneous determination of F^- and Cl^- in thorium based nuclear fuel samples at 950^oC.