O-DEVICE is a deductive object-oriented knowledge base system for reasoning over OWL documents. O-DEVICE exploits the rule language of an existing production rule system, called CLIPS and transforms OWL ontologies into an object-oriented schema of the CLIPS Object-Oriented Language (COOL). It is an extension of a previous system called R-DEVICE. O-DEVICE exploits the advantages of the object-oriented programming model by transforming OWL ontologies into classes, properties and objects of the OO programming language provided within CLIPS, called COOL. A complete list of all the transformations can be found here. The system also features a powerful deductive rule language which supports inferencing over the transformed OWL descriptions. Users can either use this deductive language to express queries or a RuleML-like syntax.