This edition marks the first publication of Rontgen's Sonata in C Minor (1911). This work was discovered while visiting the Rontgen Archives at the Netherlands Music Institute in The Hague in 2019. Being previously unpublished and unrecorded, I am grateful to Rik Hendriks at the Netherlands Music Institute for his assistance and unrestricted access to Rontgen's manuscripts. There is a single manuscript source for this work (NMI Catalogue No.107/017). It is neatly penned, and great care has been taken in it's detail. This manuscript contains no corrected notes, scratched-out errors, or pencilled-in changes. Clearly, Rontgen prepared this work for publication, but he never saw that realized. It is a single-movement sonata that should interest both pianists and musicologists. The textures, form and expressive qualities are well defined, and I believe it deserves a wider audience. I hope other pianists find the work intriguing and feel compelled to perform it. Fingering, metronome suggestions and hand re-distribution suggestions are editorial. All pedal indications are by the composer. © Mark Anderson