The core part of the thesis is focused on experimental studies of a single solid oxide cell (SOC) operating in electrolysis mode. It is preceded by theoretical description of most important issues related to electrochemical cells, electrolysis, methods of hydrogen production, power-to-gas systems and the basic principles of operation of solid oxide cells. Three chapters are devoted to theory. The first chapter is a general introduction into the topic. It highlights the importance of energy storage technologies in current, global electric energy economy indicating the related potential role of hydrogen technologies and reversible solid oxide cells. The introduction has been further extended by a brief description of historical background on the process of electrolysis. Chapters 2, 3 and 4 contain the theoretical description. Chapter two presents an overview of most important in industry technologies of hydrogen production. These include primary methods for hydrocarbons reforming (SR, CPOX, ATR) and hydrogen generation from biomass.  Next to that, general process of electrolysis is described with brief description of three main techniques: alkaline electrolysis, proton exchange electrolysis (PEM) and solid oxide electrolysis (SOE). The broadest theoretical chapter is number 3. It is devoted to detailed view on thermodynamics of solid oxide cells, cell construction solutions and materials used. There are also presented basic performance characteristics of cells working in both electrolysis (SOE) and fuel cell (SOFC) modes together with the corresponding losses and efficiencies. Chapter 4 is focused on complete power-to-gas systems including solid oxide cells. It includes description of the design, performance and evaluation of two separate hydrogen electric energy storage systems based on reversible solid oxide cells. The first is theoretical, simulated HYSYS 8.8 software, based on dedicated mathematical model. The second, on the other hand is a real system installed and operation in USA. Finally, chapter 5 is the key part that describes the experimental part of the thesis. The aim of the experiment is clearly stated, then there are presented: design of the experiment, experimental stand, the start-up procedure and graphical representation of the obtained results. The results are extensively discussed. The last chapter includes the final conclusions that are mainly focused on evaluation of the experimental procedure and guidelines for its improvement.