Two biotrickling filters and a bioscrubber system, equipped with different package materials and inoculums, were compared in regard of performance in treatment of a VOC mixture containing 70 v% of tert-butyl alcohol (TBA) and 30 v% of acetone. The average absolute elimination capacity at highest test loadings was 80.2 g Cm-3 h(-1) for the bioscrubber (BIOdek (R) and BIO-NET (R) as package material; Mycobacterium austroafricanum TBA100 and Aquincola tertiaricarbonis TBA200 as inoculum) and 25.2-27.5 g Cm-3 h(-1) for the biotrickling filters (configuration I, Bio-airSPHERES (R), no further inoculation; configuration II, Hilfow (TM) rings, Mycobacterium austroafricanum TBA100 as inoculum). However, normalizing elimination capacities to either biomass or the cell count of TBA degraders the biotrickling filter of configuration I ranked first (2.75 g C g oDM(-1) h(-1) and 12.91 g C 10(12) cells(-1) h(-1)) and the bioscrubber last, due to a largely sized regeneration unit (0.13 g C g oDM(-1) h(-1) and 0.40 g C 10(12) cells(-1) h(-1)). Even though TBA is hardly biodegradable, its biodegradation could be done without expensive formation of inoculums using Bio-airSPHERES (R) as composite package material. Performance levels were enhanced and stabilized by repetitive dosage of fertilizer in all systems. This is both the first report about biodegradation of a waste gas containing TBA and application of Bio-airSPHERES (R) for biodegradation of high VOC concentrations.