Khoaï, also referred to by its original Greek title, Χοαί, is a 1976 composition for solo harpsichord by Iannis Xenakis.

The title refers to "offerings of wine or water poured into the ground; libations and vows to the Chthonians (infernal Gods)".

[1][2][3] It was written in a period where the harpsichord was gaining momentum as a concert instrument, popularized by some Polish virtuosos such as Wanda Landowska and the dedicatee of this piece, Elisabeth Chojnacka, who collaborated frequently with Xenakis throughout most of his career.

[5] It is an extremely complex and difficult work, with many arborescent structures[6][2][7][8] and rapid repetitions of individual notes, a method Xenakis also explored in Synaphaï.

But then the difficulties appeared to me rather at the "limits" of what is possible.The dedicatee, Elisabeth Chojnacka, who also gave the piece its first public performance, said she was "completely panic-stricken by its fiendish notation" when she first received the score, despite having worked closely with Xenakis on the practicality and possibilities of the harpsichord as an instrument.