Notes: C, Db, Eb, E, F#, G, A, and Bb - Key: C - Category: Nonatonic or Ennatonic Scales
The C "Half-Whole tone" uses nine notes per octave. Because of this same reason it is a member of the so called Nonatonic or Ennatonic -scales that have Nine-note (or Nine-tone). On the piano keyboard, it is made up of four black keys: Db, Eb, F#, and Bb and four white keys: C, E, G, and A. This combination makes this scale - as well as the C Prometheus, C Prometheus Liszt, and C Prometheus Neapolitan - as great choices for composing or improvising music.
If we take a look a the key signature of the C "Half-Whole tone" Scale we can find it has three flats and one sharps. Therefore, on sheet music you will find four accidentals on the score. The notes of this scale are: C, Db, Eb, E, F#, G, A, and Bb.