ENIgnacy Daniłowicz, the 19th century scholar from Podlasie, a professor at the Vilnius University, then, successively, at the Kharkiv University, the Kiev University, and the Moscow University, left behind a rich and valuable scholarly legacy. A lawyer and historian by education, he also showed considerable linguistic and palaeographic skills and was fascinated with the language of Rus’ documents pertaining to the history of Lithuania. His work with said iles was undoubtedly facilitated by his knowledge of the dialect of Podlasie. The text focuses mainly on the methods of transposing the Supraśl letopis, written at the beginning of the 16th century in the Cyrillic script, into the Latin alphabet. The analysis of the solution used by Daniłowicz in terms of the transliteration of vowels and consonants reveals a good command of the palaeographer’s toolkit in spite of the lack of linguistic training. Keywords: palaeography, Cyrillic script, Latin script, transliteration of vowels and consonants, Supraśl letopis.