Italian opera and symphonic composer whose masterpiece was the opera L'amore dei tre re (1913; The Love of Three Kings).

After study at the Milan Conservatory, Montemezzi established himself as an operatic composer with Giovanni Gallurese (1905). L'amore dei tre re, based on a play by Sem Benelli, obtained its atmosphere of brooding tragedy from a fusion of Italian melody with elements of French Impressionism derived from Claude Debussy's Pelléas et Mélisande. It became a standard work of 20th-century opera. La Nave (1918), with a libretto based on writings by Gabriele d'Annunzio, was less successful. Montemezzi's symphonic works include Paolo e Virginia (1929) and Italia mia! (1944), which was inspired by Italy's defeat in World War II. In 1939 Montemezzi emigrated to California, returning after the war to his birthplace.