The only example of a working sixth-tone harmonium in the world belongs to the collections of the National Museum and is permanently exhibited in the Czech Museum of Music in Prague. We present here new compositions were written by Phill Niblock, Klaus Lang, Bernhard Lang, Milan Gustar, Judith Berkson, Idin Samimi Mofakham and Ian Mikyska. The premiere of these compositions took place in August 2023 as part of the Ostrava Days contemporary music festival. Performed by pianist Miroslav Beinhauer (*1993) who is recently the only musician in the world who can play this unique instrument. The first model of the sixth-tone harmonium was created in the 1920s on the basis of a commission from the pioneer of microtonal music, Alois Hába, whose visions for its construction convinced 10 the company August Förster. The improved model of the harmonium dates from 1936 by the same company. The first Czechoslovak president Masaryk supported the purchase of the new instrument by contributing ten thousand crowns, and the same amount was added by the Ministry of Education and National Enlightenment at the time. In 2018, Miroslav Beinhauer participated in the premiere of Hába's sixth-tone opera Come Thy Kingdom, followed by the staging and recording of Alois Hába's opus Sixth compositions for sixthtone harmonium, op. 37, which was the only solo composition for this instrument for more than ninety years. In the last three years, new repertoire for sixth-tone harmonium has been written by renowned Czech and foreign composers.