This paper will discuss the evolution of reactor control over the last 25 years within the DuPont Company and its subsidiaries. It will focus on high level trends in control philosophy, systems and approaches. These changes have been necessary in order to achieve higher rates, better yields, improved uptime and a more sustainable footprint. This paper is an update to an article that was presented twenty-five years ago at Chemical Process Control (CPC) 3. The main focus will be on the use of Model Predictive Control (MPC) for reactor processes. (C) 2013 Elsevier Ltd. All rights reserved.