[1] Mathieu was born into a musical family: his father was the director of a theatre in Antwerp and a singer, while is mother taught singing at the Académie des Beaux-Arts of Leuven.
In 1867 Mathieu won a second prize in the Prix de Rome contest with his cantata Torquato Tasso’s dood.
Afterwards, he returned to Brussels, where he held a position as accompanist at the Theatre Royal of LA Monnaie.
His compositions include 7 operas, 3 symphonic poems, concertos for piano and violin, a Te Deum and choral works.
His best known work today is "Freyhir", an hour-long choral tone poem written in 1883 on the theme of deforestation around Ardennes where the composer grew up.