In the times of greater need for energy savings and higher efficiency of energy conversion, Stirling engines are again receiving attention. With greater interest in engines, came a bigger need for adequate mathematical modelling of the process and of the measurement results. In this final thesis, we analyse the operating parameters of laboratory beta type Stirling engine in Microsoft Excel. Measured parameters were pressure and total volume of the working medium. We have divided the data into individual cycles and plotted the points on a p-V diagram. Then the calculation of temperature and entropy values for each measured point was done and the data were plotted on a T-s diagram. We calculated the total work done by the system for each of the diagrams with trapezoidal method. It was evident from the data, that a p-V diagram is more reliable for work, determination, than the T-s diagram, which was derived from the same data. Carnot and thermal efficiency were determined only from the given data points. The engine had with our operating conditions on average 5 % thermal efficiency, which equals to 40 % of Carnot efficiency.