Doctoral dissertation prepared under the direction of Michele Barbe and defended at Universite de Paris IV, Paris-Sorbonne in December 2004, to obtain the diploma of Docteur en Histoire de la musique et Musicologie. Abstract: The study of music in the life and work of Alejandro Xul Solar (Argentine, 1887-1963) reveals new aspects of a very particular personality. Painter, writer and linguist, but also astrologist and inventor, Xul Solar studied many subjects. The sound is integrated into a complex tissue of knowledge that finds visual form in his watercolours, drawings and oil paintings, in his puppet theatre, in his variation of chess. The invented musical notation systems, as well as the keyboards modified to allow their application, are the result of deep thought on the interrelation between the arts. His linguistic and esoteric works also show the influence of music. In order to clarify the implications of this subject, this dissertation approaches it in three stages: Firstly, the biography of the artist is presented in three chapters, emphasizing the role that music played in his life (family heritage, studies, musical relations, influence of the milieu, musical affinities, collection, etc.). Secondly, his investigation on music related aspects, such as notation, organology and the application of the interrelation of the arts, are organised in the three following chapters. Finally, the presence of music in his pictorial work is studied in the third part, by means of the analysis, sometimes accompanied by more or less audacious interpretations, of some thirty music related paintings. Xul Solar’s figure and work are at every stage placed in the historical and aesthetic context in order to comprehend their real value.