After O'Kelly closed down his publishing business he was active in various functions at the Conservatoire in Paris, including as Bibliothéquaire-adjoint and as secretary of the committee for admissions et propaganda.
He died in Paris, aged 70, on 16 February 1900 in the home of his son in Avenue Trudaine, 9th arrondissement.
His funeral service was held in Notre-Dame-de-Lorette, and he was buried on the Père Lachaise cemetery, where the grave is still extant (in Division 74).
The Magasin again changed hands after Cendrier's death in 1859, now to Edme Saint-Hilaire, further on to Émile Cellerin in late 1868, who had to close down as a consequence of the Franco-Prussian War in 1871.
His catalogue consisted mainly of piano music and songs, for which there was a great demand both for professional and home use.
[3] In fact, the vast majority of the composers he published are today forgotten, exceptions being some works by Debussy's teacher Albert Lavignac (1846–1916) and some composers who enjoyed some popularity at their time such as Antoine Marmontel (1816–1898), Henri Duvernoy (1820–1906), Georges Mathias (1826–1910), Georges Pfeiffer (1835–1908), Alphonse Hasselmans (1845–1912), Théodore Lack (1846–1921) or Marie Jaëll (1846–1925).
Examples are Marc Chautagne's La Veuve Malbrough (1872), Ferdinand Poise's Les Trois souhaits (1873), Delphine Ugalde's Seule (1875), Adrien Talexy's Garçon de cabinet (1877), Joseph O'Kelly's La Zingarella (1878) and La Barbière improvisée (1884), Avelino Valenti's Embrassons-nous, Folleville (1879), Pauline Thys's Le Mariage de Tabarin (1885) and quite a number of voluminous scores in 1881 by the recently deceased Maurice Bourges who must have left a considerable amount of money behind to have his music published posthumously.
Another large-scale vocal composition was the oratorio Agar (1875) by Georges Pfeiffer for soli, chorus and orchestra, which was published in full score.
The best-known and longest running was the École du Piano: Choix de Concertos des Maîtres.
Thus he took over the publisher Fernand Schoen in 1877 and parts of Gambogi (1877), Aulagnier (1880) and Escudier (1882, including the piano music by Louis Moreau Gottschalk).
He also had short-time partnerships with Ikelmer (1874 only), Rouget in Toulouse (1874–84), Lissarrague in Versailles (1877 only) and Naus in Paris (1880-1).