In chemical industry, especially in the case of continuous processes, operator training simulators (OTS) are becoming widely used. With the help of these systems several operation and safety issues can be analysed, and the operating staff of the plant can be trained for handling different plant failures. The main part of the OTS is the process model that replaces the real technology. Hence, in control development the simulated process variables are required to be reasonably accurate. The paper presents the structure of the process model of a batch processing unit in UniSim Design, different model constructions of a jacketed batch reactor and the identification of the parameters affecting its hydrodynamic and thermal behaviour. Construction of the process model is the first step in developing the OTS of the pilot plant located in the authors' laboratory. It can be an effective tool in the development of model-based control systems. (c) 2012 Elsevier Ltd. All rights reserved.