In a competition for young artists, organized by Venetian sculptor Antonio Canova, Kessels in 1819 won the highest award with his terracotta Saint Sebastian pierced by arrows, a piece of frank and beautiful workmanship.

In Rome Kessels taught the Liege sculptors Louis Jehotte (c. 1803-84) and Eugène Simonis, who exerted an influence through their teaching at the Académie Royale des Beaux-Arts in Brussels.

Four plaster sculptures are permanently exhibited in the museum's neoclassical department: Discobole lançant le disque (1822–23), Génie funèbre éteignant un flambeau (c. 1829), Monument funeraire de la comtesse (1830–32) and Scène du déluge [1] (c. 1836).

Among his numerous classically minded patrons was William Cavendish, 6th Duke of Devonshire, who commissioned two marble bas-reliefs, Day and Night (1819), and Diskobolos Preparing to Throw (1828), both in Chatsworth House.

For Carlos Miguel Fitz-James Stuart, 14th Duke of Alba Kessels sculpted Reclining disk thrower, now in the Accademia Nazionale di San Luca in Rome, and Cupid whetting his darts.

As he belonged to the Roman school of neoclassical sculpture, founded by Canova and Thorvaldsen, along with Johann Gottfried Schadow, Albert Wolff and others, he adhered to idealist aesthetics and to the laws prescribed by classical art.