Elastin, a scleroprotein of the connective tissue, is insoluble in water, saline or all non-hydrolytic solvents. One method of obtaining soluble derivatives is partial hydrolysis with oxalic acid. Elastins obtained from the aortic tissue of various species were hydrolyzed 5 times and 75 minutes as a modification of Partridge's method of partial hydrolysis, where 60-minute boiling with 0.25 M oxalic acid at 100 °C is repeated 4 times. Cellulose acetate, SDS-polyacrylamide gel electrophoresis and high performance liquid chromatography were used to identify the molecular mass and to control the purity of the soluble derivatives. These studies show that all soluble elastin derivative samples obtained with this method have two protein bands with molecular masses of 71,500 and 58.500 daltons which is closer to the molecular mass of tropoelastin. We believe that under these conditions of hydrolysis the purity of soluble elastin can be increased.