In 1883, Leon became one of founders of the art circle als ik kan ("if I can") in which, in particular, Henry van de Velde began, but after five years he left the group. From 1886 he was friends with Dutch artists Matthijs Maris, Jacob Maris, Hendrik Willem Mesdag, Lawrence Alma-Tadema and the Italian painter Giovanni Segantini. From 1886 he taught at the Antwerp Academy of Fine Arts. At the turn of the 19th and 20th centuries, Brunin participated in exhibitions and auctions in Belgium, France, Germany and the USA. One of his students was , to whom we owe a 1929 Portrait de Madame Léon Brunin.René Édouard-Joseph, Dictionnaire biographique des artistes contemporains, tome 1, A-E, Art & Édition, 1930,
