He studied medicine in the university of his native town, and in 1831 he became assistant in the chemical schools. He pursued the study of chemistry in Paris, Berlin and Gießen, and was subsequently engaged in teaching the science at Ghent and Liège. In 1856 he was appointed professor of chemistry in the Liège University, and he retained this post until the close of his life.
About the year 1835 he began to devote his leisure to the investigation of the Carboniferous fossils around Liège, and ultimately he became distinguished for his researches on the palaeontology of the Palaeozoic rocks, and especially for his descriptions of the molluscs, brachiopods, crustaceans and crinoids of the Carboniferous limestone of Belgium. In recognition of this work the Wollaston medal was awarded to him in 1875 by the Geological Society of London, and in 1876 he was appointed professor of palaeontology at Liège.
See Notice sur LG de Koninck, by E Dupont; Annuaire de l'Aced. roy. de Belgique (1891), with portrait and bibliography.