novel superconductive oxides are disclosed . the oxides all have layered perovskite - like crystal structure and manifest superconductivity above about 77k . an exemplary material has composition bi 2 . 2 sr 2 ca 0 . 8 cu 2 o 8 . other materials are described by the nominal formula x 2 + x m n - x cu n - 1 o 2 + 2n + x / 2 ± δ , where x typically is bi , or bi together with pb or other appropriate substituent , m is one or more divalent ion or mixture of monovalent and trivalent ion , n is an integer greater than 3 , x = p / q , where p and q are integers and p & lt ; q , and δ is less than 0 . 5 . associated with the inventive compounds typically is a superlattice structure , with t c of the compound typically being correlated with the superlattice spacing . the inventive compounds are typically relatively ductile .