Data warehouse systems provide a great way to centralize and converge all data of an
organization in order to facilitating access to the huge amounts of information, analysing and
decision making. Actually, the conceptual data-models of data warehouses does not take into
account the semantic dimension of information. However, the semantic of data models
constitute an important indicator to help users to finds its way in any applications that use the
data warehouse. In this study, we will tackle this problem trough using ontologies and semantic
web techniques to integrate and model information. The contributions of this paper are an
ontology for the field of grain trade and a semantic data warehouse which uses the ontology as
a conceptual data-model.