The object of research in this article is the chant manuscript of a five-line notation kept in the funds of the State Archive in Tobolsk (No. 306). The significance of this musical monument for the culture of Siberia is determined by its belonging to the fifth metropolitan of Siberia and Tobolsk Philotheus (Schemamonk Feodor), the first Ukrainian scholar monk at the Siberian cathedra. About belonging of the manuscript to sainted Philotheus is testifies owner's record of his pupil Peter Tungus. Sainted Philotheus played an important role not only in the education of indigenous peoples, but also in the emergence of a new European type culture in Siberia. He initiated the construction of the first stone cathedral in Siberia in the name of the Holy Trinity in the monastery of the same name and founded of the bishop's school (later seminary), the religious theater. Metropolitan Philotheus paid much attention to the issues of church singing. Thus, in the bishop's school singing “according to the note” was taught, the lord himself organized the church and metropolitan choruses from the “written out” Kiev monks and exiled Cossacks, and taught literacy and singing, including of newly baptized Siberians. Given the period (the beginning of the XVIII century) and the ancestry of Metropolitan Philotheus, cultivated by him the church-singing culture in the Siberian metropolia was under considerable influence of the South-West Russian Baroque. The manuscript being analyzed is a monument of this tradition. According to the complex of paleographic signs, the manuscript dates back to the early 1660s. and, perhaps, was created by scribes of the Kiev-Pechersk Lavra, from where Philotheus was erected to the Siberian Metropolitan Сathedra. The singing book is written in four handwritings, representing the South-West Russian semi-uncial with elements of cursive writing and a lot of outline letter, some words are given under the titles, greekized and latinized variants of capital letters are actively used. The edit of the text is pre-reform, elements of razdelnorechyie are preserved. The composition and content of the book refers to the most common from the second half of the XVII century “Oktoih” type of the Ukrainian-Belarusian Irmologion. It consists of seven parts: 1) (main) chants of the Sunday service and the irmos of the canons; 2) automelon (αυτόμελον) (samples for chanting stichera, troparia and sedalen (Κάθισμα)); 3) Irmos and other hymns to the Compline of Feasts of the Nativity of Christ and the Epiphany; 4) a fragment of the Obikhod of Quadragesima; 5) selected holidays of the Minei stikheres-book; 6) a fragment of the Obikhod of the all-night vigil of the Kiev chant; 7) full-text canons in the Palm Sunday and Easter. Thus, the structure of the Irmolion differs from the Moscow singing books of both the Old Russian and the post-reform traditions, and some differences in the repertoire of the chants are noted. The musical material of the manuscript belongs to the Kiev “izvod” (derivation) of the znamenny chant. In conclusion, it is noted that the Tobolsk manuscript is a typical Ukrainian-Belarusian Irmologion, but for the Siberian region it is undoubtedly unique. Tobolsk Irmologion together with later manuscripts in various Siberian storages form the foundation for the statement of a large-scale problem of the influence of South-West Russian Baroque on the development of the musical culture of Siberia.