A study of runaway incidents involving thermal chemical reactions in the UK over the past 25 years (1988-2013) has been carried out. The objective of this study is to determine possible causes of thermal runaway incidents. A statistical analysis of the underlying problems that led to thermal runaway incidents has been provided. A comparison of the current study on thermal runaway incidents with those identified prior to 1988 has been carried out. This study clearly shows that lessons have not been learnt from thermal runaway incidents caused by operator errors, management failures and lack of organised operating procedures. These factors have been the possible causes of about 77% of all the thermal runaway incidents analysed in this study. The number of fatalities and injuries as a result of thermal runaway incidents has increased by similar to 325% and similar to 279%, respectively, in the last 25 years even though the number of incidents was significantly less. On the basis of this analysis, several recommendations have been proposed that could help to minimise the risks associated with any thermal runaway incidents in the future. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.