Abstract: A macroporous cryogen is disclosed which has grafted thereon polymer chains formed by polymerizing at least one monomer of the general formula (I) CR1R2=CR3R4 (I) wherein R1 and R2 are equal of different and each represents a hydrogen atom or substituent group which is not detrimental to the polymerization reaction; and R3 and R4 each represents a hydrogen atom or a substituent group which is not detrimental to the polymerization reaction, provided that R3 and R4 are not both a hydrogen atom, on said macroporous cryogel. A method for the preparation of said macroporous cryogel by graft (co)polymerization and the use of said macroporous cryogel in a separation process are also disclosed.