Cells of Pseudomonas stutzeri in suspensions of TiO2 ranging in concentration from 0.5 to 4.0 g l‐1 were irradiated with a blacklight blue u.v. source displaying peak emissivity at approximately 370 mm. Irradiation under these conditions is known to result in the generation of lethal free radicals. During irradiation the suspensions were agitated, using a specially modified laboratory shaker, to ensure efficient exposure of the TiO2. A u.v. radiation dose of 175 kJ m‐2 resulted in cell fractional survival ranging from 5.5 times 10‐5, at the lowest TiO2 concentration, to 1.0 times 10‐6, at the highest TiO2 concentration. The advantages of contactors employing TiO2 suspensions are briefly compared to immobilized TiO2 systems.