This paper describes a method of preparation of permanently porous functionalized styrene copolymers by the chemical transformation of gel or macroporous styrene-divinylbenzene copolymers. As a crosslinker, tetrachloromethane was used in the presence of a Friedel-Crafts catalyst (aluminium or ferric chloride). By the modification of the macroporous copolymers, very high surface area resins, equivalent to Davankov＇s hypercrosslinked resins, have been obtained. The post-crosslinked polymers show high specific surface areas, a narrow distribution of small pores, and good mechanical stability and thermal resistance. The modification of the gel-like copolymers, because of the slow reaction rate and restricted reagent diffusion, produced copolymers with only very modest surface areas.