Intrinsic to the production and design of equipment in the eld of Chemical Process Engineering is the understanding of multiphase ows. Multiphase ow phenomena such as transport phenomena at material interfaces and the dynamics of material interfaces can be studied either through novel experimental techniques or novel computational uid dynamics (CFD) algorithms. State-of-the-art multi-scale, hierarchical approaches for understanding multi-phase ow in Chemical Process Engineering have been developed which enable researchers to better understand the interaction of individual scales in multiphase ows. e 1st International Symposium on Multiscale Multiphase Process Engineering (MMPE) was held in Kanazawa, Japan on 4–7 October, 2011 in order to discuss modern problems related to multiphase process engineering. An important purpose of the MMPE conference was to foster international collaborations amongst the participants. We were delighted to see that over 115 participants from many countries attended the MMPE symposium. A er the MMPE symposium, a call for papers to be submitted to a special issue of JCEJ, with the MMPE theme, was made to both conference participants and the readers of JCEJ. irty-three papers were submitted to this issue for review, and twentyeight papers were accepted through an iterative peer-review process. We hope that this special issue will provide a great opportunity to discuss issues related to multiscale multiphase process engineering and will be of help in disseminating to researchers the latest knowledge of multiscale multiphase process engineering. We thank the authors for their contributions, and the reviewers in providing their thoughtful and constructive comments. We also express our gratitude to Prof. Hiroyuki Honda of Nagoya University, the Editor-in-Chief of JCEJ, for his substantial support. We thank Ms. Kazuko Yamashita, in the editorial o ce, for her assistance and devotion in the preparation of this special issue.