Desire Thomassin was born on 11 February 1858 in Vienna (Austria). His father was the charge d'affaires of the Duchy of Parma in Vienna, his mother was a German from Regensburg. After the death of the father in 1867 the remaining family moved to Regensburg. There Desire Thomassin finished his school and attended the local lyzeum for two terms till 1878. Then he studied music in Munich under Josef Rheinberger (composition) and Max Hieber (violin).

Desire Thomassin mainly worked as a composer, but was not successful with his early works. For that reason he had to find a second source of income. He was a talented painter and created many pictures, but also had to work for an art dealer in Munich.

Desire Thomassin died on 24 March 1933 in Munich (Germany).

Today Desire Thomassin is better known as a painter than a composer which is irony of fate because he considered himself a composer and painting was only for breadwinning. But his paintings are nevertheless of high quality, are still sought-after today and sell regularly at art auctions.