The agreements for the peaceful use of nuclear energy reached by Argentina and Brazil are not like the traditional South American integration schemes. Historically, the latter were characterized by their interpresidential structure, which showed progress but produced a precarious level of institutionalization. Although the beginning of the "nuclear cooperation" can also be characterized by its interpresidential nature, later the course of the development turned towards supranationality, with both parties becoming complementary to the same process, previously unknown in the region, and extraordinary successful.