A systematic design methodology is developed in this work to optimize batch process schedules and water-allocation network in a simultaneous manner. The proposed model formulation and solution strategy are believed to be superior to the available ones in the following aspects. First, a continuous-time based time model is introduced and an improved state-space superstructure with SEN and STN representations is adopted to capture the structural characteristics of the integrated water-allocation network for batch process. Then, cost of splitters and mixers is added to reduce and evaluate the complexity of the network configuration. Finally, a hybrid optimization strategy integrating DICOPT and CA is developed for the resulting mixed-integer nonlinear programming (MINLP) model and, also, an interactive iteration method is adopted based on sensitivity analysis to guide the search toward a potential global optimum. Two illustrative examples are presented to demonstrate the validity and advantages of the proposed approach. (C) 2008 Elsevier Ltd. All rights reserved.