Achieving e-Government objectives requires radical organizational redesign of the public administration. This paper illustrates the results of the first stage of the applied life cycle model, used in designing a public sector ontology. Goal of the specific ontology is to achieve the elimination, or at least reduction, of diversity that appears in the public administration organizational, operational and conceptual models, as far as they depict, organize and codify the knowledge, making it accessible and reusable. Through a common semantic conceptual model, provided by the ontology, public sector bodies will become fully interoperable and able to co-operate, forming a single coherent information and communication system.