Ontologies can be used to describe common cloud functionalities and enable common terminology to assist in cloud interoperability. In this work, we have developed the ontology for resources and operations and the ontology of interoperability problems. The aim is to clearly describe and categorize the existing functionalities, features and specificities of commercial platform asaservice offers. The first ontology also provides data type mappings among different Paa Sstorages and cross-Paa Sdata types used in inputs and outputs of the remote APIoperations to provideacommon layer for information exchange and data migration among different Paa Sproviders. The ontologies were evaluated by tools and by human experts. Furthermore, the ontologies were used in cloud interoperability prototype to show their practical applicability.