As compositional characteristics of Beethoven's late period, counterpoint (fugue) and variation are often pointed out, but in Op. 109 and subsequent works, the feature of a compressed sonata form within romantic and free musical ideas can also be noted.

In this sonata, presumed to have been completed around the autumn of 1820, the first movement is stoically condensed, while the third movement, in variation form, possesses a vast expanse.

First Movement: E major, 2/4 time / 3/4 time, Sonata form

After an 8-bar main theme, the tempo immediately slows to Adagio, and the subordinate theme appears. The opening tempo is restored, and a development section based on the main theme (from bar 16) is presented.

The tempo again slows to Adagio, and the recapitulation of the subordinate theme in the tonic key (from bar 58) occurs first, followed by the recapitulation of the main theme (from bar 66) and a coda, closing the movement. It is separated from the second movement not by a final bar line but by a double bar line, indicating that the two movements are inseparably linked.

While it might be difficult to fit this rondo-like movement into the framework of sonata form, it is certain that sonata form was kept in mind regarding its tonal structure.

Second Movement: E minor, 6/8 time

This movement also appears to have been composed with a sonata-form-like tonal structure in mind. The resolute main theme is built upon a descending bass line, which resonates with the main theme of the first movement. After a transition (from bar 9), a passage resembling a subordinate theme, spun from this transitional idea, appears (from bar 33). While it is passage-like and its thematic character is weak due to its affinity with the transitional idea, its tonality clearly takes the dominant key (B minor).

The development section (from bar 66) begins with the main theme in B minor. After the bass motive is developed over an octave tremolo organ point, it transitions into a chorale-like idea with the indication una corda.

In the recapitulation (from bar 105), the transition is significantly shortened, and the movement concludes concisely after the recapitulation of both themes in the tonic key.

Third Movement: E major, 3/4 time

A theme of 32 bars, consisting of an initial 8 bars moving towards the dominant key and a subsequent 8 bars settling from the dominant to the tonic, each repeated, is followed by six variations.

• Variation 1: A figural variation is performed over a simple waltz-like 3/4 accompaniment.
• Variation 2: A harmonic variation, where the first and second halves are varied using different techniques.
• Variation 3: The time signature changes to 2/4, and while maintaining the harmonic framework, it is a two-voice contrapuntal variation that deviates further from the theme's melody than Variation 2.
• Variation 4: In 9/8 time, marked "somewhat slower tempo than the theme." Although the theme's harmonic framework is preserved, recognizable motives or figures no longer appear. It is a variation with two contrasting characters: imitative sections in three-voice (occasionally four-voice) writing, and chordal tremolos and arpeggios.
• Variation 5: In 2/2 time, it begins with a three-voice contrapuntal treatment. The choice of time signature might suggest an awareness of an archaic fuga style, but the immediate appearance of successive perfect octaves (bar 119) indicates that it is not counterpoint in the strict sense, but rather possesses such a character to a certain extent.
• Variation 6: In 3/4 time, it begins with four-voice writing, and in the first four bars, the theme's melodic line returns in the inner voices. Fragments of the theme appear above and below a double trill on the dominant, and continuous long trills, also on the dominant, in the low and high registers. Finally, the theme is recapitulated in its complete form, closing the piece.

The aria-like theme, the numerous harmonic and virtuosic variations that depart from the melodic line, and the final return of the theme cannot but bring to mind Bach's Goldberg Variations. Furthermore, the connection to the Diabelli Variations, which Beethoven had begun but interrupted composition on at this time, cannot be overlooked.