One aspect of the invention relates to a tissue adhesive medical product comprising at least 1% by weight of dry matter of an electrophilically activated polyoxazoline (EL-POX), said EL-POX comprising at least 2 electrophilic groups, including at least one pendant electrophilic group. The invention further relates to a kit for producing a biocompatible, cross-linked polymer, said kit comprising EL-POX and a nucleophilic cross-linking agent comprising at least 2 nucleophilic groups.