The passing phosphate contaminants from reactans into aluminofluoride precipitates and their phase composition were studied in relation to the solution reaction (NaF with AlF3) parameters. The degree of passage of P2O5 from the solution to the precipitate was found into be controlled primarily by the final pH of the reaction mixture and by the NaF/AlF3 mole ratio. The solid phase contained cryolite or chiolite, or a mixture of cryolite with chiolite or with NaAlF4.H2O. The adsorbability of PO43+ ions by the solid phase decreases in the descendung order: AlF3. 3H(2)O > alpha -AlF3.H2O > NaAlF4.H2O > Al(OH)F-2.H2O > Na5Al3F14 > Na3AlF6. The conversion of NaAlF4.H2O or Na5Al3F14 into Na3AlF6 by NaF is accompanied by coprecipitation of phosphates.