As a child and teen Henri Duparc showed an interest in many fields and possessed an extraordinary intellectual capacity. Yet, he also divulged a sensitive, sometimes hesitant nature. He initially began studying for a career in law, but concurrently took piano lessons from César Franck. Later he studied composition with him and soon began writing music. He typically destroyed his early works, not satisfied with aspects of his style, or with the entirety of the piece itself.
In 1868, his Five Mélodies, for voice and piano, were published, marking his first major surviving song collection. Shortly afterward he expressed doubts about three of them (Serenade, Romance de Mignon, and Le galop), though he ultimately allowed their survival. From this early period there exists a Sonata for piano and cello (1867), not published but in manuscript form, held by his daughter's estate.
In 1869, Duparc received his first substantial exposure to Wagner's music when he traveled to Munich for several performances. There he met Liszt, who introduced him to Wagner at that year's Bayreuth Festival. Wagner became a hero to Duparc, and at times a noticeable influence in his music. The composer would make numerous trips to Bayreuth over the next several decades, often with friends like Chabrier. By the early 1870s Duparc was turning toward the orchestra. In 1874 he wrote Poéme nocturne, which was premiered in April that year at a Société National concert. Only the first of the three parts, however, has survived. Also, Duparc composed the aforementioned symphonic poem, Lénore, in 1875. Four years later, still in the thrall of Wagner, though not stylistically now, he began work on his opera Roussalka.
In 1885, Duparc abruptly abandoned composition, at least in part owing to a neurasthenia, which may have had psychological manifestations. The composer had an acute sense of pain and other physical discomforts, but managed a reasonably normal life with his wife and family. Though he composed no new music after 1885, in the early 1900s he did revise some earlier works, like the 1868 Five Mélodies and the Poéme nocturne of 1874.
In the early 1900s Duparc became blind. Always a religious man and growing more so in his later years, he traveled to the shrine known for miracles in Lourdes, France, in 1906. He seemed to accept his blindness, and toward the end of his life he suffered from paralysis.