Cello Sonatas No. 1 and No. 2, Op. 5, are two sonatas for cello and piano written by Ludwig van Beethoven in 1796, while he was in Berlin. While there, Beethoven met the King of Prussia Friedrich Wilhelm II, an ardent music-lover and keen cellist. Although the sonatas are dedicated to Friedrich Wilhelm II, Ferdinand Ries tells us that Beethoven "played several times at the court, where he also played the two cello sonatas, opus 5, composed for Duport (the King's first cellist) and himself". Although Jean-Pierre Duport was one of the King's teachers, it is now thought to have been his brother Jean-Louis Duport who had the honor of premiering these sonatas.

In the early 19th century, sonatas for piano and instrument were usually advertised as piano sonatas with instrumental accompaniment. Beethoven's first violin sonatas, for instance, were published as "sonatas for piano with accompaniment by the violin." The cello sonata was especially so plagued, as it grew out of sonatas for continuo; as late as the beginning of the 19th century it was still common for the cello in cello sonatas to double the left hand of the piano part, with the piano right hand playing obbligato figurations and melodies. Beethoven, indeed, is credited with composing one of the first cello sonatas with a written-out piano part.The Op. 5 sonatas are the first two examples of fully developed cello sonatas in the modern tradition.

Both of these sonatas are in two movements, with an extended Adagio introduction preceding the opening Allegro of both of them.