Abstract: The white powdery tungstic acid prepared according to previous reports^[1,2] reacts directly with phosphoric acid solution to form a solution of 12-tungstophos-phoric acid with some other polytungstates.For purification, the solution was extracted with n-butyl ether under suitable addition of hydrochloric acid, so as to produce an oily layer which is not miscible with water and excessive n-butyl ether. The n-butyl ether layer was then stripped with water to obtain pure aqueous solution of 12-tungstophosphoric acid. On evaporation by heating, 12-tungstophosphoric acid gradually separated out as pure crystals.