In this study, an operator training simulator (OTS) has been developed for the homogeneously catalyzed two-step biodiesel production from waste cooking oil (WCO). Biodiesel from WCO leads to cheaper production and also protects the environment by utilizing WCO effectively and producing non-polluting biodiesel. Currently, many biodiesel producers use homogeneous catalyst for biodiesel production due to faster reaction and moderate operating conditions. Process safety and efficient process operations require skilled operators. OTS is crucial in operators' training as on-job training is often costly, risky and incomplete. The developed standalone OTS has been investigated for a number of abnormal process scenarios. Each scenario can be inserted by an Instructor as and when it is desired. This study demonstrates the capability of a commonly used process simulator 'Aspen Plus Dynamics' (APD) and 'Aspen OTS Framework' in OTS development for the complex biodiesel process. Process model is developed in a modular fashion that facilitates easy addition or removal of any unit operation(s) in case of process modifications in the future. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.