The industrial SO2 oxidation catalyst VK69 deactivates at around 440 degrees C in a 10% SO2, 11% O-2, 79% N-2 gas mixture. In situ EPR measurements show that the deactivation is caused by the precipitation of V(IV) compounds. DeNO(x) catalysts based on V2O5/TiO2, the TiO2 support, analytical grade anatase rnd transition metal-exchanged Al-PILCs (pillared clay) have been characterized by EPR spectroscopy and the catalytic activity of the catalysts monitored up to 500 degrees C. Depending on the exchanged metal ion, a relatively large temperature range for the catalytic activity towards the SCR reaction was observed. (C)1999 Elsevier Science B.V. All rights reserved.