Method of cross-linking hyaluronic acid with divinulsulfone

The present invention relates to methods of producing a homogenous hydrogel comprising hyaluronic acid, or salt thereof, crosslinked with divinylsulfone (DVS), said method comprising the steps of (a) providing an alkaline solution of hyaluronic acid, or salt thereof; (b) adding DVS to the solution of step (a), whereby the hyaluronic acid, or salt thereof, is crosslinked with the DVS to form a gel; (c) treating the gel of step (b) with a buffer, wherein the gel swells and forms a hydrogel comprising hyaluronic acid, or salt thereof, crosslinked with DVS.