Powder samples of the high temperature superconducting system YBCO have been synthesized with partial replacement of the Yttrium site by rare earth element according to the formula Y_1-x RE_x Ba₂ Cu₃ O_7-δ (RE= Eu, Er and Nd) where x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and1.0 mole%. The samples were checked by X-ray diffraction. X-ray analysis' show that the dominant phase is the orthorhombic phase for most samples. Also the samples were checked by Infra-red spectroscopy for determining different modes. Differential thermal analysis used to determine the melting points of the samples. The temperature dependence of electrical resistivity for all samples has been recorded and discussed. Adding rare earth elements such as Eu, Er and Nd improve the superconducting behavior, particularly at certain percentages, depending on the replacing element. Therefore we can conclude that careful replacement of the Yttrium site in the YBCO system with some rare earth elements may improve the superconducting behavior.