This article considers the cooperation between the Ukrainian and Finnish national movement in the first quarter of the twentieth century. The political aspects of the cooperation are viewed through the lens of Herman Gregorius Gummerus’ biography (1877-1948). In contemporary historiography, Herman Gummerus is mostly known for his historical studies that focus on the economic history of ancient Rome. Whereas the majority of studies on Ukrainian-Finnish cooperation in the early twentieth century contain only fragmentary evidence of his political and diplomatic activities, the author of the article considers it necessary to present the biographical essay with a special focus on Herman Gummerus’ participation in the Finnish activists’ movement during two periods of “Russification of Finland” (1899-1905, 1908-1917) and after World War One. Herman Gummerus’ attitude towards the Ukrainian national state project (including the Ukrainian State or the Second Hetmanate, dated 1918) is reconstructed on the basis of his memoirs “Ukraine on the cusp. Six months at the head of the Finnish Embassy in Kyiv” (Ukrainan murrosajoilta - Kuusi kuukautta lähetystön päällikkönä Kievissä) (1931).