The topic of this final work was to describe thermodynamic processes which can achieve the largest amount of work. It was also required to preform an analysis and process comparison. Calculations of the obtained maximal works were made using air, carbon dioxide and a gass mixture. Firstly, the maximal works were calculated for work substances which included four different gasses. The purpose was data comparison, the temperature and the mass of the gasses were already set. After that, maximal works for the same work substances were calculated. In this case the mass and pressure were set for 3 different temperatures. For every process, corresponding p-v diagram was drawn. Different work substances with the same parameters had different maximal works. In the calculations for the different pressures analyzed, the maximum amount of work can be obtained using an air of initial pressure 20 bar, while in the calculations for the different temperatures analyzed, the largest amount of work can be obtained using a mixture of gases with a temperature of 573 K. For every maximal work, data comparison was made for all set pressures, temperatures and work substances. With this final work, it is proven that initial temperature, pressure and work substance greatly affect the maximal amount of work.