Count von Manderscheid-Blankenheim´s library at Blankenheim Castle was closed after Napoleon´s army invaded the Rhineland in 1794. The last owner of the castle, Augusta and Filip Krisitan von Sterrnberg-Manderscheid took some of the books to Prague where they became parts of the Sternberg Library, which itself was incorporated into Prince Lobkowicz´s library, with which it was transferred in 1928 to the Czech National Library collection. This study provides information on the discovery of the uniquely preserved catalogue of the Blankenheim Castle library, compiled sometime between 1789 and 1794. It has been used to successfully identify a total of 29 manuscripts in the National Library collection. The study concludes with an edition of the Blankenheim manuscript catalogue and brief descriptions of the discovered codices.