
Metal oxide superconductors of the yttrium-barium-copper type (YBa.sub.2 Cu.sub.3 O.sub.4 type) can be formed by precipitation from an aqueous solution of the salts of the metals using an oxalate precipitation reagent under basic pH conditions (e.g., at least 11) to form a fireable precursor only partly in the form of the oxalate salts of these metals.











