Unlike a steam engine which has one input (fossil fuel) and one output (mechanical /electrical energy), where the working fluid (demineralised water) circulates in a closed circuit; radically new technology Seawater Steam Engine (SSE), which is the subject of this Master's thesis, from one input (solar energy or other renewable energy sources) produces two outputs (mechanical/electrical energy as one output and and drinking water as the second output). Thereby, seawater, as working fluid, flows through the system, separating into two phases, steam and liquid (salinity solution >60‰). This process takes place in a high pressure separator that represents the most technologically and scientifically demanding component of SSE technology, which is why the authors of this technology call it the "heart of the system", of whom efficiency depends the efficiency of the entire SSE system. Considering that up today there is no data of the thermal properties of seawater at temperatures over 200°C and 80 bar pressures, and that for the realization of the SSE technology are required temperatures higher than 300°C and a pressure of 80 bar, there is evidently a great space for scientific research and innovation, so it is not uncommon that on 19.06.2018. the US Department of Energy (DOE) has launched a Solar Desalination program which aims to research and develop the technology components that can produce both, energy and drinking water, in the same way as SSE technology, which is more than a clear confirmation of the importance and scientific-research potential provided by SSE technology. In the experimental part is given a short comparison of the various desalination technologies and their efficiency, analysis of key parameters for seawater separation in SSE technology, analysis and comparison of changes in the specific enthalpy of evaporation, density and salinity for water and sea water depending on temperature change in the process. The results show that by the effect of the separation of about 50%, SSE technology is in the middle of the effectiveness compared to other desalination technologies; instead of cost for invested energy for desalinization and drinking water production of 1 m^3, SSE technology even provides /produces energy in the amount of 100 kWh of energy. Also, was made a comparison of changes of specific evaporation enthalpy and density depending on temperature change in selected seawater salinity of 20 ‰, 30 ‰ and 40 ‰. Since former results are limited to data for temperatures up to 120ºC, it is obviously a space for further research of thermophysical properties of seawater. The importance of developing a high pressure separator as well as other components of Seawater Steam Engine technologies is reflected in the significance of the whole SSE technology which at today's stage of technological development of mankind is only that allows simultaneous energy and drinking water production using only three natural resources (Solar energy or the energy of another renewable energy source, Seawater and Gravity) and thus the only one has a realistic potential (may be available to both, developed and less developed countries) to supply the whole world with energy and drinking water and that way anticipate climate changes.