Abstract: In the presence of concentrate H₃PO₄ the poly(succinimide) was quantitatively polymerized by heating D,L-aspartic acid. The product quickly reacted with aminopropyl-silica, and then was hydrolyzed to poly(aspartic acid)-silica. It was found that the poly(aspartic acid)-silica stationary phase had good ability to separate proteins. The reaction conditions were also optimized during the investigation.