The piece is dedicated to Ernest Fleischmann, managing director of the Los Angeles Philharmonic from 1969 to 1997, who convinced Berio to write a Sequenza for trumpet, despite years of resistance to the idea.

Sequenza X requires the trumpeter to employ a variety of extended techniques, including flutter tonguing, pedal tones, and valve tremolos.

Like much of the extended technique for brass, Berio's incorporation of doodle tonguing was inspired by jazz trumpeter Clark Terry.

Sequenza X is the basis for Berio's Kol-Od (also called Chemins VI) which adds a small ensemble to accompany the solo trumpet part.

Kol-Od was premiered by Gabriele Cassone with the Ensemble InterContemporain, Pierre Boulez conducting, on April 27, 1996, in Basel, Switzerland.