In this paper, we report on the kinetics of phenol degradation and cell growth in continuous cultures of suspended cells of Bacillus thermoleovorans sp. A2 at 65 degrees C. A high yield coefficient of Y(x/s)=0.84 g cell dry weight g(-1) phenol was measured at a dilution rate of 0.5 h(-1). At the same dilution rate the coefficient for maintenance metabolism (m(s)) was determined to be 0.045 g phenol g(-1) cell dry weight h(-1). The maximal growth rate (wash-out) determined at a phenol inlet concentration of 188 mg l(-1) was 0.9 h(-1). Up to 7 g phenol l(-1) per day were degraded in a continuously operated 2-l stirred tank reactor with suspended cells (feed concentration 660 mg l(-1)). Additionally, yield coefficients for oxygen and ammonium are reported.