He returned to Paris from 1828 to 1829 to enter the École des Beaux-Arts and at first studied under the direction of François-Édouard Picot, then as a free student of Dominique Ingres.However, the clergy's hostility to them, the materials used, the saltpeter walls and their situation all meant that they were already deteriorated by the end of the 19th century and are now largely lost (except for Saint Martin cutting his cloak in two at St-Germain l'Auxerrois), though Mottez's cartoons for them survive.During the same years he frequented the Bertins' salon, alongside the main writers and artists of the time (a sketch of his for a portrait of Victor Hugo survives).After the 1848 Revolution Mottez set out for the United Kingdom, where he produced several portraits of British nobles and personalities and the exiled minister François Guizot, which were exhibited at the Royal Academy salons.He returned to France in 1853 and worked with Delacroix at the Église Saint-Sulpice, at the start of the 1860s, where their highly opposed styles clearly showed the struggle between the neo-classical and romantic visions.