The phase equilibria of the system Bi2O3-SrO-CaO-CuO with emphasis on the High-T(c) superconducting compound Bi2Sr2Ca2Cu3O10 have been studied. For the preparation of single phase Bi2Sr2Ca2Cu3O10-samples the exakt stoichiometry is not likely, because it is not stable. For the processing of Bi2Sr2Ca2Cu3O10- samples the preparation of samples exhibiting a little excess of CuO and Bi2O3 is recommended.