AbstractA process for the recovery of thorium from monazite has been developed using cellulose phosphate as a selective cation‐exchange material. The ore is broken down with sulphuric acid and the leach liquor passed through columns of cellulose phosphate where thorium is preferentially adsorbed, and from which it is subsequently eluted with 10% ammonium carbonate solution. It has been shown that leach liquors with a high iron content require preliminary reduction with aluminium before adsorption. A typical concentrate contains >90% thoria and <4% phosphorus pentoxide. The optimum conditions for preparation of the adsorbent and for operating the process have been determined.