The LNCS Journal on Data Semantics is devoted to the presentation of notable work that, in one way or another, addresses research and development on issues related to data semantics. The scope of the journal ranges from theories supporting the formal definition of semantic content to innovative domain-specific applications of semantic knowledge. The journal addresses researchers and advanced practitioners working on the semantic web, interoperability, mobile information services, data warehousing, knowledge representation and reasoning, conceptual database modeling, ontologies, and artificial intelligence. Volume XIII constitutes a special issue on semantic data warehouses. The papers in this volume address several topics within this relatively new domain, providing different insights into the multiple benefits that can be gained by envisioning data warehouses from a semantic perspective. These papers broach many new ideas to be addressed in future work.