A linear, low-order input/output model is identified for a nonlinear distributed parameter system using a combination of singular value decomposition and the Karhunen Loeve expansion. The model captures the dominant behavior of the system around a nominal operating point. A quadratic dynamic model-based controller (QDMC) is designed based on this low-order model. Sufficient conditions for closed-loop stability are presented and proven. The system identification method and the resulting QDMC controller are demonstrated on a nonlinear multiple-input multiple-output (MIMO) chemical reactor that produces benzene from the hydro-dealkylation of toluene. (C) 2003 Elsevier Ltd. All rights reserved.