This study focuses on the microstructural and spectroscopic analyses of a strongly linked (melt-joined) seam between two superconducting pieces. The long-term objective is to identify microstructural phenomena that need to be controlled in order to modify superconducting transport through a joined interface. When a large domain of superconducting Y-Ba-Cu-O (YBCO-123) was cut and mechanically joined, the zero distance levitation force was reduced to 70% of the original value due to disruption of flux lines through the interface. When identical cut pieces were joined using a lower melting point superconducting powder (Yb-Ba-Cu-O (Yb-123)) as solder, 92% of the original value of zero distance levitation force was recovered. This indicates that the seam created by this method is effective in significantly restoring continuity of flux Lines through it. This opens up the possibility of building bigger superconducting components of any desired shape, by melt-joining individual pieces. This paper describes the microstructural characteristics of the interface observed using Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of X-rays (EDAX) and X-ray Photoelectron Spectroscopy (XPS). (C) 2000 Elsevier Science B.V. All rights reserved.