Solid electrolytes are the dense electrolyte membranes that mainly allows ionic conductors to pass through them and block electronic conductivity. The present book is a part of dissertation work on Bismuth based zirconia system. In this work, we have reviewed the role of bismuth based Zirconia system and also investigated systematic doping on bismuth by zirconia. The synthesized material is characterized by various techniques and their applicability is investigated using ac conductivity and thermal expansion behavior study. The conclusions and future scope of the present work is also mentioned in brief. The present book is very helpful for beginners who wish to work on solid electrolyte materials for SOFC applications.