Commettant studied the piano and musical composition at the Conservatoire de Paris (1839–1843) and made a long tour in the United-States from 1852 to 1855 as a soloist.

Comettant later visited Philadelphia, Washington, D.C., Richmond (Virginia), and Charleston, then spent a month in Mobile in a cotton plantation.

On his way to New Orleans, he sailed on the Mississippi and went through Vicksburg, Memphis and Louisville, where he took the opportunity to admire Mammoth Cave and ended his journey by Cincinnati and Pittsburgh.

Unlike many travelers, Comettant focused on American society and institutions; the great spaces of nature were indifferent to him.

Comettant went again on a journey in 1864 and visited Denmark, then in July 1888 was appointed French juror at the Melbourne Centennial Exhibition (1888) where he arrived 6 September after he left Marseille 1 August.