Nowadays, an ever-increasing amount of libraries provide their data as linked open data - LOD. Subject headings and thesauri terms are provided online via Internet with the employment of adequate semantic technologies, such as triplestores of LOD and their corresponding SPARQL endpoints. Following the examples of major libraries worldwide, we decided to convert the existing service of interactive information retrieval that is provided by the University of Piraeus digital library of Thesis and Dissertations into a service compatible with LOD. The service through the Graphical User Interface – GUI gives the opportunity to the end-users to navigate to the subject headings of the digital library through the employment of broader and narrower terms and as well through the employment of any common subdivision that may share. At the same time, the users can find information from other repositories that provide their data as well as LOD (i.e. the articles’ database of New York Times). This paper is structured as follows: Initially, the basic principles and the components that are necessary to participate in the LOD cloud are analyzed. Then, the example of Library of Congress is presented, which provides subject-based information as LOD since 2008. The next section presents the process that was followed to create the local LOD triplestore and demonstrates its connection with other LOD-compliant data sources. Finally, the GUI of the service is presented, followed by some general conclusions.