This document attempts to present the piano music of Claudio Santoro, a major twentieth century Brazilian composer. In order to illustrate the composer's background, the first chapter addresses briefly the situation of Nationalist music from the beginning of the second decade of this century to the 1940s, when Claudio Santoro came into the Brazilian scene. A general discussion about the Modernismo movement initiated by Mario de Andrade and the opposed views to the later school by the group Música Viva - headed by Hans Joachim Koellreuter - illustrates the politics and sociology in the music scene in Brazil during the first decades of the twentieth century. A biography, focusing mostly in a personal account by the composer, serves to illustrate Santoro's family background, environment, education and struggles to develop into a first class musician. The compilation of Santoro's piano music and an overview of its characteristics, introduces pianists to this Brazilian composer, whose body of works include mostly orchestral music. Although not a pianist himself, he composed several valuable piano works worthy of the repertoire. The Fourth Sonata represents one of Santoro's most popular piano works. The analysis of this work focuses on clarifying how the structure may be organized and how the chromatic idiom supports Santoro's deceptive tonal goals.