The paper concerns the validation of the selected issues related to the new ontology-based approach to the elaboration and management of evidences prepared by developers for the IT security evaluation process according to the Common Criteria standard. The evidences are implied by the claimed EAL (Evaluation Assurance Level) for a developed IT product or system, called TOE (Target of Evaluation). The evidences envisage the TOE features and its development environment. The validation and use of the author’s elaborated ontology are discussed, including: composing evidences for the given TOE and EAL, expressing details of evidences documents, issuing queries to get given information about model, etc. The paper also shows how the evidences are organized, developed and used. This work is aimed at the development of a prototype of a knowledge base, designed mainly for developers to allow them to compose and manage different kinds of evidences elaborated on the patterns basis. This knowledge base can be used by a software tool aiding developers who produce evaluation evidences.