Abstract. In this paper, we present a new ontology-based formalism for representing patent information. The framework defines concepts and relations for the major aspects of patent information pertaining to patent metadata, patent content structure, patent semantics, and patent classification. Each aspect is logically covered by an individual ontology module. The paper further discusses aspects of ontology learning and integration of non-textual information for the patent domain. Keywords. Patent Information, Semantics, Ontology Learning