This thesis analyzes the electrification of ferries with the aim of reducing harmful emissions and greenhouse gas emissions caused by the combustion of fossil fuels in ship engines. Using an energy system optimization software package, four different configurations were analyzed: a diesel, an all-electric, a plug-in hybrid and a hybrid. In the introduction, environmental regulations and technical measures for decarbonization were discussed, with an emphasis on electrification as a key technical measure. The analysis included a life-cycle cost calculation (LCCA) and the application of the HOMER Pro software package to configure the system. The technical description of the analyzed ship provided the basis for the development of various models of the ship's power system, while the results of the simulations offered their detailed features. Finally, the paper concludes that for the analyzed ship Petar Hektorović, an all-electric power system is the most cost-effective configuration with regard to life cycle costs. It is important to note that there are challenges related to charging infrastructure and coastal chargers. Electrification of ferries offers significant environmental and financial benefits, but requires careful planning and significant investments in coastal infrastructure which has not been considered in this paper.