Abstract: A process for the preparation of crystalline perovskite powders consisting essentially of primary particles uniform in nanometer or micrometer size and uniform and near spherical shape and of narrow size distribution, of the general formula A.sub.x (BO.sub.3).sub.y, wherein cation A is at least one metal selected from the group comprising Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+ and La.sup.3+ and B in the anion (BO.sub.3) is at least one metal selected from the group consisting of Ti.sup.4+, Zr.sup.4+, Sn.sup.4+, Hf.sup.4+, Nb.sup.5+ and Ta.sup.5+, x is equal to the valence of the anion (BO.sub.