His fascination for medieval music was first aroused while reading the Belgian musicologist François-Joseph Fétis’s "Revue Musicale" (musical revue). The first musicological work by de Coussemaker dates back to 1835. Even today his works remain a reference for matters relating to medieval musicology through their punctuality and precision: "Mémoire sur Hucbald et ses traités de musique" (1841), "Histoire de I'harmonie au Moyen Âge" (1852), "Les harmonistes des XIIe-XIIIe" (1864), "Œuvres complètes du trouvère Adam de la Halle" (1872). His compilations "Scriptorum de Musica Medii aevi", 1864–1876, continue those by Prince Abbot Martin Gerbert. Among these historical writings, the "Troubles religieux du XVIe dans la Flandre maritime (1560-1570)", published in 1876, particularly merits being remembered.