The resarch was carried out to investigate the effect of the variation of the nominal composition of the compound Bi2 Sr2 Ca2 Cu2 On2 for different values of n, as well as the effect of the addition of PbO as a dopant to the calcined powders of these compounds. High - Tc superconducting samples of such such compounds have been prepared by solid state reaction method. The composition of these was analyzed by XRD patterns, resistivity measurements by for probe technique and the morphological analysis by scanning electron microscope (SHM) The research included the determination of the proper preparation conditions required to obtain Bi - 2223 compound with the highest Tc. These parameters are; the forming pressure of the pellets, the sintering temperature and time, and the flow rate of oxygen during the process of sintering. Two types of samples with nominal composition Bi2 Sr2 Ca2 Cu3.O10 were prepared, taking into consideration the optimum preparation conditions, the first type prepared without adding PbO, and the second type with PbO doped by 5% wt. of the calcined powder. The results showed that the highest Tc obtained for the Pb - free samples was about 105 K, while that of the Pb-contained samples was -about 130 K. The Pb- contained samples required lower sintering temperature (845 848C") to obtain the high Tc phase. Therefore, it is concluded that the doping of BSCCO compound with Pb is essential for the enhancement and the stabilization of the high Tc phase. The study of the superconducting behavior ol the high — Tc samples with different values of n reveals that Tc increases with increasing n up to n=3.5, where the highest value of Tc (206 K), was obtained for the Bi - based compounds. Further increasing of n to values greater than 4 has negative effect on the value of Tc. It was concluded that the best Bi-based nominal composition is Bi2 Sr2Ca2.5Cu3.5 O13+ω.