A liquid anion exchange resin N-1923 has been used as an extractant,for thorium. The mechanism is; (R-NH3)2 SO4(OR) + Th(SO4)3(2-)=(R-NH3)2Th(SO4)3(OR) + SO2-4(AR) The metal which forms a sulphuric complex `anion with the resin is extra- cted. Alkali and RE metals have no interferences; REE, U,Ti,. Zr, cad, be eluted by 3 M-H2S04; fernxic ion can be masked by ascorbic acid. The menthod is suitable for determining Th heighet then 0.000x% in ores.