The book deals with a brief study on a new class of high temperature superconductors (La-Ba-Ca-Cu-O) with special emphasis on their crystal structure, electrical transport and magnetic properties. It contains five chapters as follows: Chapter 1 starts with historical overview; where, the discovery of superconductivity followed by many hall mark discoveries in experimental and theoretical superconductivity have been reviewed briefly. Theoretical background on excess conductivity, fluctuation magneto-conductivity, critical state models and the derivation of magnetization using critical state models are reviewed. Chapter 2 describes the experimental techniques used for sample synthesis and characterization. In chapter 3, the detailed analysis of thermodynamic fluctuations induced excess conductivity on selected samples of the above series with and without magnetic field are presented. In chapter 4, the temperature and ac field amplitude variations of ac susceptibility have been discussed. Finally in Chapter 5, the important conclusions drawn from the physical measurements and analysis carried out on the above series of superconducting materials are summarized.