a superconducting material is disclosed which includes oxides of metals having the following composition : . sub . 1 - v ca . sub . v ). sub . 2 cu 2 wherein a is at least one element selected from the group consisting of y , la , nd , sm , eu , gd , ho , er , yb and mixtures of at least one of y , la , nd , sm , eu , gd , ho , er and yb with at least one of tb , tm and lu , x , y , v and z are numbers satisfying the following conditions : 0 ≦ x ≦ 0 . 4 , 0 . 1 ≦ y & lt ; 0 . 7 , 0 ≦ v ≦ 0 . 2x , and 2y - 0 . 4 ≦ z ≦ 2y + 0 . 2 with the proviso that 0 . 6 - x ≦ z & lt ; 1 . 0 when 0 ≦ x ≦ 0 . 2 and that 0 . 4 ≦ z & lt ; 1 . 0 when 0 . 2 ≦ x ≦ 0 . 4 . the superconducting material is produced by providing a blend of compounds of the metals in the metal oxides , and heating the blend at an oxygen partial pressure p of at least 0 . 001 atm and temperature of ° c . to ° c .