Abtract: The Q5COST format has been designed and implemented with the aim of develop a Common Data Format for promoting code interoperability in Quantum Chemistry. Open Babel is a chemical toolbox designed to speak the many languages of chemical data. This document try to be a step by step guide about the use of the Q5COST binary format (based on HDF5, a unique technology suite that makes possible the management of extremely large and complex data collections) and how to integrate it on OpenBabel.

Keywords: Quantum Chemistry, Q5COST, OpenBabel,HDF5.