Over 75% of Benin's population have no access to formal financial services, banks and microfinance institutions combined, and women are 33.00% less likely than men to have cell phones. Thus, of the 27% of women who use their cell phones for financial transactions, 63.8% are in unions (i.e. 24.3% of women in unions who use them) (INStaD, 2019). This situation raises the following question: what factors explain the use of Mobile Financial Services (MFS) by these women in union to carry out financial transactions? With a view to addressing this concern, this study aims to contribute to improving knowledge of the factors that explain the use of Mobile Financial Services among women in union in Benin. To achieve this, we start from the hypothesis that the institutional, economic and community contexts directly influence the use of Mobile Financial Services, and indirectly through the characteristics of the household and the individual characteristics of the woman in union.