Open government data is a valuable resource of information addressed to a significant number of recipients. However, this information is usually published in raw format, i.e. without following specific guidelines and remains unexploited. Linked data technologies, on the other hand, aim at transforming data published in web sites into a machine readable format (usually RDF using URIs) in order for them to be linked to other external datasets. Regarding Greek Governmental sites, little work has been done towards this direction. An interesting case is the information provided in the ERMIS Greek portal for Public Administration which involves service provision according to the Directive 123/2006/EC. In this paper, we present a case study on the application of linked data technologies on Greek open government data located in the ERMIS Greek Government portal for Public Administration (www.ermis.gov.gr). In particular, we focus on examining how this information can be transformed into linked data in order to be appropriately interconnected to equivalent information found in web sites of other European countries and we propose solutions.