The National Gallery in London has a couple of oil-sketches by him; from its site:
"By profession a lawyer, Jean-Michel Cels was the son of the Belgian Neo-classical history painter and long-time director of the Académie de Tournai, Cornelis Cels (1778-1859). Cornelis no doubt introduced his son to oil sketching, which he had practised early in the 19th century during a seven-year stay in Italy. A number of drawings and oil sketches on paper by both Cornelis and Jean-Michel entered the art market in 1997. Besides these sketches, however, little is known about Jean-Michel's artistic activities."