Abstract. The rapid increase on the circulation of data over the web has highlighted the need for distributed storage of Internet-accessible information due to the rapid increase on the circulation of data over the web. Thus, access control mechanisms should also be distributed in order to protect them effectively. A recent idea in the access control theory is the delegation and revocation of rights, i.e. the passing over of one clients rights to the other and vice versa. Here, we propose an XML-based distributed delegation module which can be integrated into a distributed role-based access control mechanism protecting networks. The idea of X.509v3 certificates is used for the transfer of authorization information referring to a client. The modules are XML-based and all of the associated data structures are expressed through Document Type Definitions (DTDs).