This invention relates to a stable composite material comprising a support member that has a plurality of pores extending through the support member, and a macroporous crosslinked gel that is located in, and fills, the pores of the support member, in which crosslinked gel is entrapped a stabilizing polymer, which stabilizing polymer is neutral, linear or branched, non-crosslinked, and substantially water-insoluble. The presence of the stabilizing polymer is such that it allows the composite material to largely retain its porosity and morphology after being dried. The invention also relates to a process for preparing the stable composite material described above, and to its use. The stable composite material is suitable, for example, for separation of substances, for example by filtration or adsorption, including chromatography, for use as a support in synthesis or for use as a support for cell growth.