A separation medium in macroporous gel form is disclosed which is obtainable by cooling an aqueous solution of at least one gel forming polymer to a temperature, at which the solvent in the system is partially frozen with the dissolved substances concentrated in the non-frozen fraction of the solvent, said gel forming polymer being selected from the group consisting of polymers normally forming gels too fast when an aqueous solution thereof is cooled to a temperature within a range below 0.degree. C. to enable the formation of a cryogel and said cooling being carried out in the presence of at least one chaotropic agent in said aqueous solution in order to prevent gel formation before the polymer solution is frozen. The use of said separation medium for diverse separation purposes is also disclosed.