The microbes of Pseudomonas putida (KCTC1768) were fixed on the biofilter-packing media comprising an equivolume mixture of granular activated carbon (GAC) and compost, by recycling the liquid medium containing incubated Pseudomonas putida (KCTC1768). A biofilter experiment was performed to observe its transient behavior under the operating condition of 2,180 ppmv of ethanol-inlet concentration and 158 g/m3/h of ethanol-inlet load for the five consecutive temperature-stages of operation ranging from 25 ℃ to 40 ℃. For the five temperaturestages of operation their removal efficiencies were measured and were compared with each other. The optimum operating temperature of the biofilter turned out to be ca. 30 ℃, which was consistent with the previous experimental result of Lim and Park. However, the optimum incubation-temperatures of Pseudomonas putida (KCTC1768) and the equivalent (i.e., NCIMB8858) were announced to be of 26 ℃ and 25 ℃ by Korea Collection for Type Cultures (KCTC) and National Collections of Industrial, Food and Marine Bacteria (NCIMB), respectively. It was also confirmed by the experiment in which the microbes were incubated in the same liquid medium as in the previous work of Lim and Park at temperature ranging from 20 ℃ to 40 ℃ and their growth rates were subsequently measured. Thus, the optimum operating temperature of a biofilter inoculated with Pseudomonas putida (KCTC1768) was proved to be 30 ℃, which was higher than its optimum incubation-temperature by ca. 5 ℃.