The present invention describes a new class of cross-linked derivatives of partially N-deacetylated hyaluronic acid or derivatives thereof, comprising at least one repeating unit of formula (I) hereinafter depicted and a process for the preparation of said cross-linked derivatives, comprising a multicomponent condensation reaction involving the carboxy groups and the amino groups originating from a partial N-deacetylation of hyaluronic acid or derivatives, together with an aldeyde and an isocyanide. The derivatives thus obtained can be used, alone or in association with biologically and/or pharmacologically active substances, for the preparation of pharmaceutical compositions, biomaterials, surgical and healthcare articles, slow release systems and for the coating of biomedical objects.