The chalumeau (plural chalumeaux; from Greek: kalamos, meaning "reed") is a woodwind instrument of the late baroque and early classical era, in appearance rather like a recorder, but with a mouthpiece like a clarinet's.

The word "chalumeau" was in use in French from the twelfth century to refer to various sorts of pipes, some of which were made of cane and featured a single "reed" cut into the side of the cane itself (see Similar instruments).

In the late seventeenth century an improved form of the chalumeau was developed. This baroque chalumeau represents the link between the recorder and the clarinet, and is essentially a cylindrical bore recorder with a mouthpiece like that of a clarinet and two additional "throat" keys controlling notes at the top of the fundamental register. The chalumeau continued to develop for several decades alongside the clarinet, and it has a large repertoire in 18th century orchestral and chamber music.

The clarinet was developed from the chalumeau primarily by displacing the B? key up towards the mouthpiece, reducing the size of the hole and inserting a register tube; here it still produces B?, but functions in addition as a register key, allowing the upper range to be easily sounded. In addition the clarinet's mouthpiece was modified to improve performance in the upper register, and the chalumeau's straight foot joint was replaced by a flared bell.