The Grand Duo Concertant, Opus 48, J204, is a three-movement work for clarinet and piano composed by Carl Maria von Weber from 1815 to 1816. It is a virtuosic piece for both instruments. Weber most likely composed the work for himself (on piano) and his friend Heinrich Baermann, a leading clarinettist of the era, although it has also been suggested that the intended clarinettist was Johan Simon Hermstedt.
The three movements are as follows:
- Allegro con fuoco
- Andante con moto
- Rondo: allegro