Biofiltration of reduced sulfur compounds such as hydrogen sulfide has been mainly applied to emissions at mild temperatures (25 to 35 degrees C). However, an important number of industrial gaseous emission containing sulfur compounds, from diverse industrial sectors (petroleum refinery, cellulose production, smelting, rendering plants and food industries) are emitted at temperatures over 50 degrees C. Most of the studies on thermophilic systems report that a higher elimination capacity can be obtained at elevated temperature, allowing the design of smaller equipment for the same loading rate than that required for removing the same load under mesophilic conditions. A biotrickling filter inoculated with Sulfolobus metallicus, which operates at three different residence times, 60, 80 and 120 s, and two different temperatures (45 and 55 degrees C) for treating H2S is reported. The input loads of H2S were progressively increased from 0 to 100 gS/m(3). The aim of this study was to determine the capacity and ability of S. metallicus to oxidize H2S at high temperatures. The better removal capacity of H2S obtained was 37.1 +/- 1.7 gS/m(3) h at 55 degrees C for a residence time of 120 s. The difference of the removal capacity of H2S between the two temperatures was 4 g/m(3) h on average of sulfur removal for the different residence times.