Welcome to the proceedings of the 2005 International Conference on High P- formance Computing and Communications (HPCC 2005) which was held in Sorrento (Naples), Italy, September 21-23, 2005. Withtherapidgrowthincomputing andcommunicationtechnology,thepast decade has witnessed a proliferationofpowerfulparallelanddistributed systems and an ever-increasing demand for the practice of high performance computing and communication(HPCC). HPCChas movedinto the mainstreamof comp- ing and become a key technology in determining future research and devel- ment activities in many academic and industrial branches, especially when the solution of large and complex problems must cope with very tight timing sch- ules.TheHPCC2005conferenceprovidedaforumfor engineersandscientists in academia,industry,andgovernmenttoaddressallresultingprofoundchallenges, and to presentand discuss their new ideas,researchresults, applications and - perience on all aspects of high performance computing and communications. There was a very large number of paper submissions (263), not only from Europe, but also from Asia and the Paci?c, and North and South America. All submissions were reviewed by at least three Program or Technical Committee members or external reviewers. It was extremely di?cult to select the pres- tations for the conference because there were so many excellent and interesting submissions. In order to allocate as many papers as possible and keep the high quality of the conference, we ?nally decided to accept 76 regular papers and 44 shortpapersfororalpresentations.Webelievethatallofthesepapersandtopics not only provided novel ideas, new results, work in progress and state-of-the-art techniques in this ?eld, but also stimulated the future research activities in the area of high performance computing and communications.