Ostap Biliavskyi started his creative activity in 1760, when the traditions of the local artists’ guilds were still preserved. The artist had a lot of orders and was popular with customers in Lviv. There are a significant number of portraits painted by Ostap Biliavskyi. The portrait of Krzysztof Deyma is considered to be a masterpiece by Ostap Biliavskyi. It is known that the portrayed man was an active figure of Stavropigion and posed for the artist, being over the age of 50. The portrait shows a waist-length image of Deyma. The look of his brown eyes is directed to the side. The features of the man's face are depicted in detail; the posture of the portrayed person is reproduced with the same accuracy. Admiring the passementerie of his kontusz and the illusory reproduction of the texture of various fabrics, it becomes clear enough why this artist was so popular. The soft and warm colours of the portrait, light reflexes on the white satin zhupan, and a skillful detailing of portrait elements create an image imbued with lyricism and intimacy.