This graduate thesis starts with a brief overview of DC-DC converters. The basic principle of operation is described and the most important topologies are listed. In the next section of the thesis, a description of flyback converter is given. This converter can operate in continuous and discontinuous conduction mode. In continuous conduction mode, the current through the inductor never decreases to zero during the switching period. A detailed analysis was performed and typical waveforms of current and voltage are shown for operation in continuous conduction mode. In addition, the advantages and disadvantages of this converter are highlighted and its field of application is specified. The main advantage of the flyback converter is the simplicity of its realization, due to the small number of required components. It is mainly used for powering low power applications. Compared to other topologies with galvanic isolation, the flyback topology usually achieves a lower level of efficiency. Therefore, in order to reduce losses, designers developed different techniques to improve efficiency. This paper analyzes the three techniques that contribute most to the overall efficiency improvement of the flyback converter. Also, some of the efficiency improvement techniques were simulated using the Plexim PLECS simulation platform for power electronic systems.