We have discovered new high-Tc oxide superconductors in the Bi Sr Ca Cu O system with no rare earth elements. The high-Tc phase, with Tc of about 105K, greater than that of YBa 2Cu 3O 7 by more than 10K, appears to have the approximate composition of Bi 1Sr 1Ca 1Cu 2O x. As the composition deviates from this value, a low-Tc phase with Tc of 75–85K tends to appear. In this oxide system, the coexistence of Sr and Ca is essential to realize the high Tc. The chemical compositions of the high and low- Tc phases are estimated to be Bi 4Sr 3Ca 3Cu 6O x and Bi 4Sr 3Ca 2Cu 4O y, respectively. The crystal structure of both phases is body-centered orthorhombic with a=0.54,b=5a=2.7and c=3.08nm. This structure is layered structure with such that alternating Bi 2O 2 and perovskite layers occur along the c-axis. A modulated structure with highly strained a-c lattice planes is observed by high resolution TEM when the electron beam is incident along the a-axis direction.