A series of ceramic superconductor compounds with the composition LaxY1-x Ba2Cu3O7-δ are prepared by solid state reaction from the principle routs like La2O3, BaCO3 and CuO with high purity 99.99%. Different measurement is made to show the improvement in high phase superconductor such as resistivity measurement and the X-ray diffraction (XRD). When (x=0.20 and 0.80; x=0.40 and 0.60) an orthorhombic phase is appeared with lattice constants (a= 3.844 Å, b=3.912 Å, c=11.839 Å) and (a= 3.871 Å, b=3.881 Å, c=11.748Å), respectively. This emphasizes the formation of a high temperature superconducting phase. At x=0.5 a phase is changed to a tetragonal where the superconductivity is lost. From the resistivity measurement, the highest (Tc) value is found equals to (97K) for (x=0.20 and x=0.80) comparable with the YBCO-compound which does not normally exhibited Tc-value greater than (95K). The increase in Tc-value may be attributed to the amount of (La) and / or the oxygen content in the mixture which both influence the properties of the compound and are essential for the superconductivity phase.