Kinetic characteristics of n-butyl alcohol and iso-butyl alcohol in a composite bead biofilter were investigated. The microbial growth rate of n-butyl alcohol was greater than that of iso-butyl alcohol in the average inlet concentration range of 50-300 ppm. The microbial growth rate was inhibited at higher inlet concentration, and the inhibitive effect in the concentration range of 50-150 ppm was more pronounced than that in the concentration range of 150-300 ppm. The degree of inhibitive effect for n-butyl alcohol was more sensitive than that for iso-butyl alcohol in the concentration range of 50-150 ppm. The zero-order kinetic with the diffusion rate limitation could be regarded as the most adequate biochemical reaction model. The biodegradation rate of n-butyl alcohol was greater than that of iso-butyl alcohol in the average inlet concentration range of 50-300 ppm. The biochemical reaction rate was also inhibited at higher inlet concentration, and the inhibitive effect for iso-butyl alcohol was more pronounced than that for n-butyl alcohol. The factor of the chemical structure of compound was more predominant in the microbial growth and biochemical reaction processes. The maximum elimination capacity of n-butyl alcohol and iso-butyl alcohol were 55.7 and 34.8 g C h(-1) m(-3) bed volume, respectively. The compound with no side group in the main chain would be easier biodegraded by the microbial. (c) 2007 Elsevier Ltd. All rights reserved.