This study demonstrates that in the cationic ring-opening polymerization of cyclic esters, leading to biocompatible and biodegradable polymers, catalyst and initiator could be efficient when are in the same molecule (CINICAT). This is in contrast to the known processes when organocatalysts (e.g., protonic acids) require addition of an independent initiator and then low molar mass catalyst is left free in polymer. We have shown that hydroxymethyl phosphonic acid and 11-hydroxyundecaphosphonic acid act simultaneously as catalysts and initiators, becoming stable end-groups of the macromolecules (MALDI and DOSY). It follows from kinetic analysis that polymerization with these CINICATs is living/controlled. (C) 2020 Elsevier Inc. All rights reserved.