The solid-state conversion of basic magnesium, calcium, zinc, and lead compounds into corresponding crystalline phosphates by the BPO4 method has been investigated at 800 degrees C and 900 degrees C. Magnesium hydroxide carbonate is converted at 800 degrees C into Mg2P2O7 (85%), whereas calcium hydroxide gives 2CaO . P2O5 . B2O3 at 900 degrees C. Zinc oxide gives at 800 degrees C the mixture of Zn2P2O7 (90%) and Zn-3(PO4)(2) (10%), whereas at 900 degrees C only the former is obtained. In the presence of KCl, at 800 degrees C, zinc oxide yields KZnPO4, while PbO gives Pb-5(PO4)(3)Cl.