The article is devoted to the history of creation and functioning of the library of Orenburgh Branch of IRGS during the pre-revolutionary period. Formation and development of the library are considered on the basis of archival materials and records, taking into account the information contained in scientific works reflecting the scientific understanding of the past. The analysis is given to the bibliopolical sources, including printed materials of the Orenburgh Branch of IRGS. The fundamental principles of historicism and scientific reliability, logical and statistical methods allowed recreating an overall picture of activity of the library of OBIRGS. Formation of the library took place due to the support of local researchers and the public. Replenishment of the library’s fund happened mainly at the expense of donations and the book-exchange, to a lesser extent by purchase of editions. The library of OBIRGS appeared to be the storage of local history editions; its fund was substantially replenished with the local periodical press reflecting various data of local history character, so necessary for employees of OBIRGS to carry out scientific research in the region. The article considers such specific features of the OBIRGS library as implementation of double functions of scientific and public library, and a peculiar transformation — the change of borders of a service zone for readers. The emphasis is made on the role of the library of OBIRGS in the formation of scientific and cultural capacity of the region and its contribution to development of domestic book culture.