Nearly twenty years ago YBCO was the first superconductor discovered with a transition temperature above the boiling point of liquid nitrogen, the .fascinating. limit for high temperature superconductivity. From the day forward, the interest in this ceramic compound has not diminished. YBCO is one of the most promising materials for the application of high temperature superconductors (HTS) because it is able to carry a technically useful current density in applied fields at 77 K. A lot of experiments guided to investigate the basic properties of the HTS and to further the theoretica understanding of them also used YBCO, because this progress has been achieved in the preparation of bulk samples, and especially thin films deposited by a various methods. The aim of the experimental investigation presented in this thesis was to produce high quality epitaxial Lutetium doped YBCO thin films on MgO substrates prepared by pulsed laser deposition. For this purpose, bulk Lu2O3 powder was mixed into YBCO by using solid-state reaction method and pressed to make a stoichiometric target for PLD process. KrF excimer laser was worked at 14 Kv with repetition rates ranging from 3 to 5 Hz to deposited Y0.9Lu0.1Ba2Cu3O7-. thin films at a substrate temperature of 800 oC. The surface of the films were characterized by employing XRD, SEM, EDX and AFM techniques.