Xavier Marie Georges Théodore De Theux de Montjardin was born in Sint-Truiden, Limburg, Flemish Region, Belgium on 23 September 1838.

[2] De Theux obtained a Doctorate of Law.

[3] He married Eugénie de Thysebaert in Namur on 18 May 1865.

[3] Xavier de Theux served as president of the society, with Ferdinand Van Der Haeghen as vice president, Gustave Hagemans as treasurer, and Jules Delecourt as secretary.

[4] Xavier de Theux died in Brussels on 13 December 1896.