Abstract: The invention provides a method of preparing water-insoluble polysaccharide sponges, and sponges obtained by means of the method. The method comprises: (a) providing an aqueous solution of a soluble polysaccharide; (b) freezing the solution; (c) treating the frozen solution with a water-miscible organic solvent such as isopropanol to effect solvent exchange for the water in the frozen solution; and (d) drying the resulting polysaccharide material. The organic solvent contains a cross-linking agent such as calcium chloride to render the polysaccharide water-insoluble in the solvent-exchange step (c). The resulting materials are more conformable and less friable than freeze-dried polysaccharide sponges.