A separation method for W and Mo from peroxoacids solution by thermal decomposition wasstudied. Thermal decomposition of peroxotungstic acid and peroxomolybdic acid was investigated respectively. The results confirmed that peroxomolybdic acid showed a preferable stability compared with peroxotungstic acid. This thermal stability difference was the basic principle of theseparationof W and Mo. Experiments were performed to study the effects of temperature, stirring speed, free acid concentration and Mo concentration on the separation efficiency. The results indicated that peroxotungstic acid decomposed into tungstic acid（H2WO4） and precipitated selectively,while Mo was rejected in aqueous solution,realizing good separation of W and Mo. The separation factorof W and Moreached 112 under the studied conditions, which indicated that this method has potential for use in separating W and Mo.
