Task of this Bachelor work is comparison of elementary thermodynamic cycle processes. The process comparison was performed for the same amount of heat available in the heating tank and for the same amount of working medium. The comparison was done over the thermal efficiency. To calculate the thermal efficiency, it was necessary to calculate the work and taken heat. Work and taken heat is calculated via pressures and temperatures. This paper has shown that Carnot's circular process has the highest thermal efficiency, and thus it has the highest level of work, that is, the lowest taken heat. The reason for this is that Carnot's circular process has biggest difference between temperatures of available heat and taken heat. In calculation, an ideal Carnot cycle process was considered in which the isothermal temperatures are equal to the temperature of the heating and cooling tank. For this reason, the Carnot process is a reversible process. In addition to the comparison of elemental circular processes, this paper includes a description of all ten elementary circular processes and an introduction to the circular processes themselves. Each process is shown in p-V and T-diagrams.