The paper presents an application of electrical tomography for imaging a nylon polymerisation process at elevated temperatures (up to 275 degrees C) and pressures (up to 22 bar). The process was realised within a metal walled tank using a sensor constructed in the form of a ceramic sleeve with electrodes coated on the inner surface. The images obtained show the dynamic behaviour of the process and how the electrical properties of the material varied with time. (C)2000 Elsevier Science S.A. All rights reserved.