A melting-and-solidification manufacturing method for manufacturing an ingot of a high critical temperature superconductive oxide belonging, in particular, to the YBaCuO, BiSrCaCuO, or TlBaCaCuO families, wherein:an ingot of oxide having the appropriate stoichiometery is used;the ingot is held horizontally by levitation on a film of gas inside a furnace;the ingot is melted;a vertical thermal gradient is established inside said furnace such that nucleation starts at the bottom portion of said ingot;while maintaining said thermal gradient, the overall temperature of the furnace is lowered at a rate of not more than 0.1.degree. C./hour down to the temperature which corresponds to complete ingot solidification; andfinally, conventional oxygenation treatment is applied to said ingot.