Schoenberg's last solo piano work, Op. 33b, was completed in just three days in October 1931 in Barcelona. Like Op. 33a, which shares the same opus number, this piece is a short work composed using the twelve-tone technique, employing four types of tone rows: the prime form, its inversion transposed up a major third, and the retrograde of each. However, apart from these facts, there is unfortunately no plausible reason why these two works were grouped under the same opus number.

This piece is written in binary form. In the opening four measures, the first theme is presented using the prime form and its transposed inversion. This section, corresponding to the A section of the binary form, consistently features a slow tempo and soft dynamic markings. When the time signature changes from 2/4 to 6/8, a somewhat more melodic second theme appears (from m. 21). In contrast to the A section, this B section is rich in changes of tempo and dynamics. After both sections reappear, the piece enters a coda in 4/8 time (from m. 57). The coda consistently features soft dynamic markings, with the register gradually descending and the tempo progressively slowing down. The final note, a B double-flat in the lowest register, corresponding to the first note of the prime row, is also striking.

While both themes and sections are indeed contrasting, a commonality can be found in the use of contrapuntal row material, such as a main melody and a counter-melody. The background for the use of contrapuntal writing in this piece is that Schoenberg was, at the time, in the process of composing his opera Moses und Aron (unfinished) for orchestra using the twelve-tone technique. These characteristics of Schoenberg's last solo piano work would reappear in his Piano Concerto, Op. 42 (1942).