The purpose of this study was to determine the effect of acetylation process, applied during protein insulation from the chosen legume seeds, on the functional properties of obtained hydrolysates. From the lentil, vetch and two varieties of pea, proteins were extracted and chemically modified with acetic anhydride at the same time. Proteins in the extract were precipitated in point of the smallest solubility (pH=pI). Received coagel was desiccated by centrifugation and drying to obtain protein concentrates. Unmodified protein concentrates were prepared analogically, except no acylating agent which was added during extraction. Protein concentrates were hydrolyzed with tripsin and than desiccated by lyophilisation. Solubility of the protein, water and oil absorption, emulsifying activity, emulsion stability, foam capacity and foam stability were determined in hydrolysates modified and native (control) proteins. Modification of legume seeds proteins with acetic anhydride in general had improved functional properties in analyzed protein hydrolysates. Solubility of protein hydrolysates from chemically modified proteins was higher than those obtained from native proteins in case of lentil and pea (Spp. Grapis), however the solubility decrease has been noted for pea Piast. Studied protein hydrolysates possessed hight ability to water absorption, about 300% and oil absorption in range 60-69%. Acetylation increased water absorption (with the highest percentage of 74%) and oil absorption of 4-7%, for every analyzed hydrolysates. Emulsifying activity and emulsion stability also increased, achieving maximum value 50% and 46% respectively, for modified vetch protein hydrolysates. Foam properties for hydrolysates received from chemically modified proteins also had shown higher figures than native samples. The highest increase foam capacity about 25 ml and foam stability about 22 ml were characteristic for pea (Spp. Grapis). The foam capacity was not differ significantly only after chemical modification of hydolyzed vetch protein.