The aim of the current research is to identify the style of building toccata at Debussy in terms of the Tonal sources, and the harmonic combinations that he used in building the toccata, and the research followed the descriptive approach (content analysis), and the study sample consisted of the piano toccata in the scale of E /Major, which is the only author of this kind of musical works, the results of the research showed that Debussy used Major and Minor scale, the pentatonic, the third,

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... h, fifth and octave harmonicas, triple and quadruple harmonies, and vertical harmonies with wide distances and within a range of more than an octave, and also used enharmonic notes. The research recommends providing musical notes of Debussy's compositions, increasing interest in 20th century compositions, encouraging students to study and analyzing those compositions, conducting more research on toccata throughout different ages and having different authors, as well as providing audio libraries with audio recordings of Toccata, in order to allow scholars to listen, study and analyze that literature.