In D-flat major, Allegro non troppo, 2/4 time. There is a gap of over 20 years between this piece and the preceding Impromptu No. 3. It possesses a lively character while simultaneously conveying a somewhat profound atmosphere. Hence, it conveys an impression that is seemingly bustling yet tranquil. Throughout the entire piece, the music progresses through constant modulations. The section in C-sharp minor, Andante molto moderato quasi adagio, 3/4 time, takes on the character of a nocturne. The concluding section is written in C-sharp major, which is the enharmonic equivalent of the tonic key.