Abstract: This is a process for fabrication of nickel-oxide insulation on a superconductor. The process utilizes; reacting oxygen-free nickel powder with oxygen-free carbon monoxide generally at 50.degree.-75.degree. C. to produce a nickel carbonyl, separating the nickel carbonyl from reaction by-products and excess reagents by cooling the carbonyl and decanting the nickel carbonyl liquor, and contacting the carbonyl to a surface of a wire containing superconductor or superconductor precursors in an atmosphere containing a controlled amount of oxygen, with the wire at 50.degree.-800.degree. C. to produce nickel suboxide insulation on the wire. The purified nickel carbonyl and oxygen may be alternately (rather than simultaneously) introduced, to deposit a series of metallic nickel films on the wire, each of which metallic films are then oxidized to a nickel suboxide.