This study is about the determination and consideration of the works kept in Sheikh Mosque which is already a historical tekke (dervish lodge) mosque in Guneyce village, in Ikizdere County, in Rize. Sheikh Osman Niyazi Efendi (1828-1909), one of Ahmed Ziyauddin Gumushanevi's caliphs, constituted a library containing manuscript and printed books in his tekke. When this library went to pieces in the process of time, the remained books were kept in a room under the tekke mosque. These books of the library that was founded by his own devotions of Sheikh Osman Niyazi Efendi, are largely about religious sciences. Though most of the books were printed, there are certain amount of handwritten manuscripts. These works that are not reachable easily because of the location of the mosque have been perishing very fast because of the humid climate of the region and the insects. This study is necessary because the count and the list of the books in the library have not been published yet. So, a study of consideration and determination was conducted by examining all the manuscripts and printed books kept in the mosque.