Protein hydrolysates have a high biological and nutritional value and are widely used in various sectors of the food, medical, and pharmaceutical industries. This article deals with the chemical hydrolysis of the milk protein casein in the presence of hydrochloric or sulfuric acid and reports the hydrolysis parameters minimizing the loss of amino acids. In casein hydrolysis, peptide bonds of protein molecules break to form di- and tripeptides and free amino acids, enhancing protein absorption by the body. Inadequate intake of digestible forms of protein leads to disruption of growth processes and impairs the immune resilience of the human body. To avoid the decomposition of labile amino acids, hydrolysis was performed with triply distilled 6 M hydrochloric or sulfuric acid in a vacuum in sealed ampoules for 4, 8, or 24 (В±0.05) h at a temperature of 110 В± 5В°C and a substrate-to-acid ratio of 1 : 15, 1 : 20, or 1 : 25. The compositions of the casein hydrolysates obtained at various hydrolysis times are presented. For a more detailed evaluation of the properties of the casein hydrolysates, the hydrolysis time effect on the molecular weight distribution of proteins and peptides has been investigated. The problem of obtaining protein hydrolysates with the desired composition and properties remains topical.