Abstract: A superconductive element containing magnesiumdiboride (=MgB2), comprising at least one superconductive filament (1) of a size between 5 and 500 micron, which is enclosed in a metallic matrix (2) and also comprising at least one highly conductive ohmic element (4),the superconducting filaments being separated from the matrix (2) and from the conductive ohmic element (4) by a protective metallic layer (3), the superconductive filament being formed by a reaction between boron (B) and magnesium (Mg) powders and boron carbide (=B4C) powders as a first additive is characterized in that one or more additional powder additives containing carbon are present in the reaction of the powder mixtures including Mg, B and B4C. The reaction of the powder mixture to MgB2 is carried out at temperatures between 500 and 760° C. leading to a maximum of the critical current density, Jc, at temperatures at 760° C. and below.