Results of investigations of reaction conditions of monoethanol amine (MEA) with triple copolymer of α-olefins (C7-C9) with maleic anhydride and styrene have been presented. The influence of temperature, mole ratio of components and reaction time to transformation degree of anhydrides groups have been estimated by content of hydroxyl and carboxyl groups at the reactions products. When adjusted for results of mole ratio of copolymer and MEA 1:3, the content of hydroxyl groups in the case of MA-St-H was 6.6 % (cal. 6.5%), MA-St-Oc 6.1% (cal.6.34%) and MA-St-N 5.9% (cal. 6.2%). By increasing of mole ratio MEA, the founded amount of hydroxyl groups exceed the calculated that can be explained by intermolecular interaction between excess of MEA and carboxyl-groups which became free.