The son of a judge in the Dutch East Indies, Hanlo grew up with his mother, who was a Roman Catholic bigot, in Deurne, later in Valkenburg aan de Geul, both in the south of the Netherlands.
His most famous poem, 'Oote', meant as a rendering of children's speak in written sounds, was published in 1952.
It resulted in a minor scandal, when it was read aloud in the Dutch parliament as an example of art that should not be subsidized by the government.
Hanlo was an amiable, shy man, who found pleasure in relating with boys.
Jan Hanlo is still a valued Dutch author, his poems have been put to music several times.