When he was 13, he became the church organist at San Lorenzo in Damaso (Saint Lawrence in the House of Damascus), a parish church in Rome. He had also started writing music including an oratorio, "Martirio de' gloriosi Santi Giuliano" and a mass. In 1766, Sir Peter Beckford, heard him playing the harpsichord. He took Clementi back to England with him, so that he could provide the musical entertainment at Beckford's house in Dorset. He died in Evesham, Worcestershire, after a short illness.