His work focuses on the daily habits of the 19th-century middle class and the historical lives of earlier Flemish masters. In pieces like Adriaen Brouwer bij zijn leerling J. van Craesbeek, he reconstructs the studio atmosphere of the Golden Age. He avoided the stiff formality of academic portraiture. He chose to depict crowded markets and musical competitions. His studies of individuals, such as Brussels: Young Girl in a Cape, show his interest in local costume.

Collectors value Madou for his ability to document specific moments in Belgian history without excessive sentimentality. His architectural prints provide a clear record of lost city views and public buildings. The neutral tones and balanced compositions of his lithographs suit contemporary interiors. These works document the social structures and public gatherings of the 1800s. They remain popular for their historical honesty and clear execution.