A superconductor is produced by electric discharge explosion flame spraying of a composite body of constituents of an immiscible alloy. The electrically discharged composite body is deposited on a substrate and the resultant alloy is oxidized to yield an oxide of the alloy having superconductive property. This process can be applied to the Ln-Ba-Cu system (Ln is at least one of the rare earth elements including Y), typically the Y.sub.1 Ba.sub.2 Cu.sub.3 - or Y.sub.2 Ba.sub.4 Cu.sub.8 system, or other immiscible alloy systems such as the Bi-(Ca, Sr)-Cu system to form an oxide thereof.