The International Conference on Computational Science is an annual conference that brings together researchers and scientists from mathematics and computer science as basic computing disciplines, researchers from various application areas who are pioneering computational methods in sciences such as physics, chemistry, life sciences, and engineering, as well as in arts and humanitarian fields, to discuss problems and solutions in the area, to identify new issues, and to shape future directions for research. ICCS 2015 in Reykjavík, Iceland, will be the fifteenth in this series of highly successful conferences. Located in the North Atlantic Sea between Europe and America, Iceland is world-renowned for its stunning nature and inspiring culture (see the location page for more information on Iceland and Reykjavík). Since its inception in 2001, ICCS has attracted increasingly higher quality and numbers of attendees and papers. Average attendance each year is about 350 participants. The proceedings series have become a major intellectual resource for computational science researchers and serve to both define and advance the state of the art of the field. An archive of the previous meetings is available through the Previous ICCS conferences page. Out of the submitted full papers to the main track and workshops, we will select some 30% high-quality papers for presentation at the conference and publication in the proceedings. These are published by Elsevier in the open-access Procedia Computer Science series and indexed by Scopus, ScienceDirect, Thomson Reuters Conference Proceedings Citation (former ISI Proceedings) – an integrated index within Web of Science. The papers will contain linked references, XML versions and citable DOI numbers.