The quantitative factors of biogas production are mostly influenced by the raw material composition and quality. The greater is the calorific value, the faster and more effective is the decomposition process, the more biogas is produced. Thus the hydrolysis stage of raw substrate is rather important in the biogas production process. During this process the soluble components are solved, the long carbohydrate structures are decomposed to the shorter ones and water soluble oxygen is consumed. Thus the hydrolysis equipment improves raw material consumption effectiveness, increases biogas yield and its methane concentration. The hydrolysis process takes place from several hours to several days and its effectiveness is higher at lower temperature of the medium, if compared to the biogas production in the anaerobic reactor. Thus the hydrolysis process is carried out in different tanks by maintaining the necessary conditions. According to the biogas plant capacity, the equipment quantity that is used for the substrate hydrolysis can vary from one to several units, and their volume is by way smaller than the one of anaerobic reactors, and it comprises from several hundred to some thousand m3.