Polycondensation of dimethylolurea leads to the formation of a gel or a film according to the experimental conditions. Both forms of the polymer would be characterized by a specific chemical structure, i.e., dimethylene ether or diaminomethylene, respectively. We studied both forms of dimethylolurea polymer by XPS and have shown that it is possible to distinguish them using this technique. The study of the carbon peak shape attributed mainly a dimethylene ether structure to the gel and a diaminomethylene structure to the film.