Microbial detoxification of acrylonitrile vapor was performed using Rhodococcus ruber immobilized into rings of a synthetic silicone polymer (ImmobaSil(TM)) sponge. The immobilization matrix was used as both the cell support material and also as the trickle-bed column packing. The elimination capacity of the biocatalytic scrubber was determined for different influent concentrations of gaseous acrylonitrile. The working life of the non-growing biocatalyst was also examined undertest conditions and was found to be at least 70 days before biocatalyst replacement was required. An elimination capacity of 4.0 kg m(-3) h(-1) was achieved with a 95% removal efficiency, and an elimination capacity of over 7.2 kg m(-3) h(-1) acrylonitrile was achieved with a removal efficiency of 90%. This elimination capacity is 10 times that previously published in the literature. (C) 2004 Wiley Periodicals, Inc.