This paper is an archaeographic publication of an updated and expanded transcription of the accounting book of the Treasury of the Genoese Caffa for 1441–1442. This document preserves the earliest evidence of that time of the founder of the Crimean khan dynasty – Hacı Giray (1441–1466) and his fierce struggle for the throne of Crimea with rivals, namely Seyid Ahmet II (1432(?)–1455) and Genghis Kasim ben Ulug Muhammed. The document also contains numerous data on various aspects of the economic life of the most important Genoese trade factor in the Black Sea. This document significantly expands the source base to the history of late medieval Ukraine.