Deactivation of postcombustion emission control catalysts is discussed with the main focus on supported platinum and palladium catalysts. Sintering due to accidental temperature rise results in support and metal sintering worsening the catalyst performance. The impact of support material and metal precursor on sintering is elucidated. Poisoning by sulfur, phosphorous and metals diminishes catalyst activity. Measures for preventing catalyst deactivation are discussed. (C) 2004 Elsevier Ltd. All rights reserved.