Château Sociando-Mallet is located in the commune of Saint-Seurin-de-Cadourne, ten kilometres north of Pauillac, in the Haut-Médoc appellation. A document dating from March 1633 refers to land here belonging to an aristocrat of Basque origin named Sociondo. A member of his family was Bishop of Bayonne. Another document, from 1750 mentions vines belonging to Demoiselle Anne de Sossiondo. Due to various misspellings over the years, "Sossiondo" became "Sociando".

Jean Gautreau discovered Sociando-Mallet when looking for a wine estate to buy on behalf of a Belgian client. It was love at first sight, despite the fact that the property was in a sorry state. However, the terroir was excellent and the domain afforded a magnificent view overlooking the Gironde Estuary.  There were only 5 hectares of vines at the time. The buildings were in bad shape and there was no barrel cellar – just a small vat room and garage. With help and advice from Gérard Cler, a previous employee at the château, Jean Gautreau made an acceptable first vintage and a superb second one. He was helped by the fact that Sociando-Mallet's extraordinary terroir, consisting of Günz gravel with clay subsoil, is propitious to growing excellent Cabernet Sauvignon and producing wines with wonderful freshness. Jean Gautreau expanded the vineyard year after year by buying vines from his neighbors. Seeking the best possible quality, he also renovated the estate’s buildings, built a barrel cellar, and gradually improved the choice of grape varieties, matching the appropriate ones to each vineyard plot.

Today, the property stretches over a total of 120 hectares, of which 83 are under vine. Jean Gautreau sold his négociant business in 2000 to focus on managing his wine estate. He passed away in October 2019, leaving his daugther and only child Sylvie the property she had been managing since 2015. She favours viticultural methods close to nature, following in her father’s footsteps, with the same love and respect of the land. She can be found participating in the various technical tastings and choosing the blend with her team.