Recently, multi-objective optimization (MOP) has been highly required to deal with complex and global decision environment toward agile and flexible manufacturing. To facilitate its wide application, in this paper, we have developed a new and novel method named MOON2 (multi-objective optimization with value function modeled by neural network (NN)), and implemented it on the Internet as a Web-based application. By that, everyone can engage in MOP readily regardless of his/her deep knowledge about MOP. Also its client-server architecture requires us to prepare only a web browser, and realizes the ready usage independent of users' computer configuration and free from maintenance of the software. Outlining the solution procedure of MOON2 and explaining the system configuration, we provide an illustrative example regarding the usage of the proposed system. (C) 2004 Elsevier Ltd. All rights reserved.