Abstract: Organic materials, for example halocarbons, hydrocarbons or halogenated hydrocarbons are recovered from fluid streams, such as air or water, by passing these streams over post-cross-linked asdorptive porous resin beads. These beads have been prepared by(a) haloalkylating cross-linked copolymer beads of i) styrene or an alkylstyrene and ii) divinylbenzene and/or trivinylbenzene,(b) purifying the haloalkylated copolymer beads,(c) swelling the haloalkylated copolymer beads in an inert organic liquid and post-cross-linking the swollen beads in the presence of a Friedel-Crafts catalyst. The cross-linked copolymer beads which are used in the haloalkylation step are microporous copolymer beads of i) 99.8 to 98.2 weight percent of styrene or an alkylstyrene and ii) 0.2 to 1.8 weight percent of divinylbenzene and/or trivinylbenzene, based on the total weight of i) and ii).