An unfinished sonata. The name "Reliquie" (meaning "relic" or "posthumous work") comes from its designation in the 1861 first edition. Although the third and fourth movements are incomplete, the first two movements alone possess more than sufficient length and presence, often leading to performance opportunities. A completion by Ernst Krenek (1921) also exists. Similarities in movement structure and detailed articulation with the subsequent Sonata No. 16 suggest it is sometimes interpreted as a preliminary study for that work, but it is certainly not a mere stepping stone. In particular, the colorful breadth achieved through modulation in the first movement is also a characteristic feature of his later works in other genres.

First Movement: Moderato, C major, 4/4 time. Sonata form.

Even for Schubert, who was fond of modulation, such bold harmonization is unprecedented in his earlier sonatas. The key of C major and the tonally ambiguous melody in unison at the beginning hint at music that freely wanders through all keys. Along with the harmony, syncopated rhythms and emphasized notes created by appoggiaturas and accent marks powerfully tighten the music.

Second Movement: Andante, C minor, 6/8 time.

A lyrical movement consisting of three themes of differing character.

Third Movement: Minuet. Allegretto, A-flat major, 3/4 time.

The Trio section is complete, but the Minuet section breaks off just short of completion.

Fourth Movement: Rondo. Allegro, C major, 2/4 time.

The music is blank beyond measure 272. As this movement is filled with very light and joyful episodes, its unfinished state is particularly regrettable.