In this work the influence of turbulent mixing on the course of two parallel chemical reactions (neutralization of sodium hydroxide and hydrolysis of ethyl chloroacetate) is investigated for a process carried out in a semibatch stirred tank reactor. The multi-scale nature of the process is highlighted by a time-scale analysis of controlling process mechanisms. Two reactive mixing models of different complexity, both accounting for all relevant phenomena from the micro- to the macroscale, are applied for the simulation of the process. Computational results of both models for various operating conditions are compared with experimental data, thus highlighting the strengths of the two models. (C) 2004 Elsevier Ltd. All rights reserved.