In 1920, he married Claire Dumont, heiress of Hippolyte Dumont, industrialist in the sector of the extraction of lime and dolomite.
In 1889 Hippolyte Dumont, his father-in-law, established the Carrières et Fours à Chaux Dumont-Wautier, at Hermalle in Belgium.
In 1924, Léon Lhoist founded the Etablissements Léon Lhoist, a lime and dolime (dolomitic lime, or burnt dolomite) producer, at Jemelle, Belgium.
In 1926, Lhoist established the Carrières et Fours à Chaux de Dugny in France.
This business-related Belgian biographical article is a stub.