R. rubrum grew in the presence of millimolar concentrations of SeO32- under anaerobic conditions and in continuous light (10 W/m2). Selenite affected the growth rate: the end of growing phase was reached already 36 h after inoculation in control cultures, but only after 58 hours in the presence of 0.5, 1 and 2 mM SeO32- with generation times of respectively 12.2 h, 13.7 h, 14.2 h and 16.6 h In the 2 latter cultures, a decrease in optical density (A650) occurred 4 to 6 hours before the stationary phase. It coincided with the beginning of the reduction process, the appearance of volatile selenium and of a peak at 420 nm in the absorption spectrum. The uptake hydrogenase (Hup) activity has been followed in intact R. rubrum cells. Generally, anincrease in activity was observed 12 h after inoculation in a fresh medium. In the control cultures and in the presence of 0.5 mM selenite, the activity of Hup showed regular fluctuations during the growth and the stationary phases with periods of about 12 h. When selenite was present, fluctuating Hup activity stopped with the SeO32- reduction, after which it dropped. At 1 and 2 mM SeO32-, the low level of Hup was accompanied by a gas overpressure. The high selenite resistance and conversion capacity of R. rubrum could be useful in the perspective of bioremediation of this pollutant.