Charles Masson (1894-1971) was one of the leading architects of the interwar period in Nancy. People are still studying the effects of this historical and architectural period in Nancy and Lorraine. Adopting the classic form of an architectural monograph, this thesis both contributes to these studies and tries to broaden the study by mentioning the patrons. First of all, it focuses on the life of this architect, born in Moselle when Moselle was a part of Germany and whose German upbringing gives his work a unique character. Masson's oeuvre consists of 57 buildings, which have all been defined, studied, and collected together in a catalog, which constitutes the third volume of this thesis. Geographically, they are primarily located in Nancy and almost half of them are located in the famous Parc de Saurupt, the Mecca of Art Nouveau architecture and where Masson invested a lot of his time and effort, but when it comes to the types of buildings, he only designed villas, houses, and apartments. There are no public buildings in his work. Masson is unique in having only worked on residential architecture in Nancy. The 41 identified patrons are therefore all individuals, who all come from a variety of backgrounds and social classes, generally belonging to the wealthy bourgeoisie. This thesis not only looks at the life and work of Masson, but also attempts to understand the relationship between the architect and his clients, an issue which up to now, as far as the architecture of the interwar period is concerned, has not been treated seriously or systematically. It is one of the primary goals of this thesis to try to address the nature of Masson's clientele head-on. For this, the archives have proven essential, but no correspondence has yet been found despite the vast majority of the plans drawn up by Masson having been preserved. We supplemented this by carefully studying the social profile of each patron and by examining the plans and architecture of each building. We were able to identify their biases and estimate the client’s wishes, whether they dreamed of owning a luxury villa or were looking for a bargain property. This study has revealed an unknown architect from Nancy, who despite the importance of his work, has helped contribute to the knowledge of the domestic architecture and the clientele of the architects of the interwar period