This invention uses a novel approach for the fabrication of low temperature superconducting (LTS) magnesium di-boride (MgB₂) wire or cable. This approach employs the use of a "high temperature fiber or tape" as a high performance substrate material. High temperature fiber substrates are low-cost, round, light-weight, non-magnetic, and capable of withstanding, without degradation, the high reaction temperatures necessary to form the superconducting phase of Mg—B.