The present project, as it is being revealed by its title, is dealing with the research and the restoration – conservation of two manuscripts of 16th cen-tury from the Manuscript Collection of the Byzantine and Christian Museum of Athens, in combination with the theoretical study of manuscripts that be-long to the Byzantine and Post – Byzantine Era. The first post – byzantine manuscript codex that is being examined, has number of list Kolyba 53/ BXM 19756 and it belongs to the D. Loverdou – Kolyba Collection, while the second has number of list xf 24(2116)/ BXM 19602, and belongs to the Collection of the Christian and Archaeological Soci-ety. Both codices contain missal texts that are limited in certain selected Litur-gies. After the concise theoretical study of Byzantine and Post – Byzantine manuscripts, it is presented a detailed description and study of both codices. Later on, the reasons of deterioration are being presented, as well as the ethi-cal matters we had to deal with, before the conservation of codices and their rebounding. At the end, certain proposals are being deposited, with regard to the environmental conditions and the way that they can be stored and exhib-ited. After the conclusion and the bibliography, the two annexes contain the conservation reports of the manuscripts.