This paper presents some major issues related to the preparation, negotiation process, the work of the respective scientific teams and interdepartmental exchange of unknown Ottoman documents between two of the richest archival repositories – the Ottoman State Archives to the Prime Minister (Istanbul, Turkey) and the Ottoman Archival Fund at the Oriental Department of the National Library “St. Cyril and St. Methodius” (Sofia, Bulgaria). Among the most important issues and topics for analysis are: Diplomatic-Palaeographic Characteristics (type of documents); amount of Ottoman documents received on agreed exchangeand how to change the public and private perceptions of historical fact on the basis of the new information contained in them.