Renowned for his geological studies, Jean-Baptiste d Omalius d Halloy also pursued a far less known anthropological career. In different editions of his main work, the first Belgian armchair anthropologist tried to divide the world population into races, branches, families and peoples. As a true figure of transition between the 18th and 19th century, he used both human and natural sciences to establish his racial classification, based on natural characters and geography, but also evolution, history and language. Influenced by both William Frederic Edwards and Paul Broca, d Omalius often defended polygenist views, despite his catholic and monogenist conviction and his refusal to accept the multiple origin of humankind. It is also notable that d Omalius, like Tacitus and Montesquieu before him, claimed that the sole origin of humankind could to be situated in Northern European, which for d Omalius still represented the homeland of the most civilized races. Critical of the Aryanmyth , he stated that Germanic culture and language had spread over Asia and not the other way around, an argument that caused conflict within learned societies and at international conferences. For the first time, based on new archival material, this article offers an overview of Belgian anthropology before the creation of Société d Anthropologie de Bruxelles in 1882.