It gives us great pleasure to edit this special section on "Towards High Performance Computing in the Cloud," which contains papers from a number of high-profile authors in the field. These contributions were submitted via an open call for papers. All papers were rigorously reviewed and chosen on the basis of excellence and on the insight which they afford to the subject. As a result of the call for papers, twenty (20) articles were submitted and six (6) contributions were selected, resulting in an acceptance rate of 30%.HPC workloads have unique requirements in terms of performance, resource requirements and storage. However, several issues, such as interconnection speeds, data locality, placement of VMs and partial support for specialized hardware, limit the effectiveness of HPC applications in the Cloud.Nevertheless, in spite of ongoing challenges, recent years have seen HPC workloads migrating to the Cloud. This migration is driven by the desires to leverage novel B George A. Gravvanis