Abstract: The number of Internet users and the number of accessible Web pages are ever increasing day by day. It is becoming difficult for users to find relevant documents to their interests or needs. Thus whole process of finding relevant document is becoming time consuming. In this paper, we report on research that attempt information retrieval based on a user profile. A user can create his own concept hierarchy and use them for web searching which attempts to reveal expected documents to user. Ontology models are used to represent user profiles in personalized web information retrieval process. Many models make use of any one of the global knowledge base or user local information for representing user profiles. We attempt a personalized ontology model for knowledge representation. This model uses ontological user profiles based on a world knowledge base and user local instance repositories. It is observed that superior representation of user profiles can be built by using user concept models and it is found that the ontology model improves performance of web information retrieval.