Allegro moderato, C major, 4/4 time.

Written in sonata form. Similar to Piano Sonata No. 1, D 157, an attempt to modulate to a distantly related key is evident already in the exposition. The first theme is presented majestically in unison in C major, and after being established with different accompanying textures, it proceeds through a half cadence (m. 23) that seems to turn to A minor, leading to a B major triad (m. 37) that anticipates E minor. From there, by suddenly shifting to a D major triad, the second theme is presented in G major (m. 45). As the texture changes, flat keys such as B-flat major and E-flat major appear, and the parallel minor, G minor, also makes fleeting appearances, but the movement concludes in G major with the final cadence.

In the development section, attempts at constant modulating harmonic changes are observed. Beginning in C-sharp minor, it passes through G minor and E-flat minor, modulating freely to F major/F minor.

From measure 118, the opening theme is recapitulated in the subdominant key of F major. The concept of beginning the recapitulation with the first theme in the subdominant key and returning to the tonic with the second theme is already seen in Mozart's Piano Sonata in C major, K. 545. This movement concludes with a grand finale in C major.

The virtuosic writing in this movement also shows the influence of Clementi, who swept across Europe and developed piano music.