The subject of the present invention is a process of preparing a crosslinked gel of at least one polysaccharide or one of its salts, including at least the steps consisting in: a) providing, at a temperature below 35° C., an aqueous gel including at least one polysaccharide in an uncrosslinked form together with at least one difunctional or multifunctional epoxy crosslinking agent b) maintaining the mixture of step a) at a temperature below 35° C. for at least one hour c) stimulating the crosslinking reaction of the mixture obtained after step b), and if need be d) recovering said crosslinked gel formed.