In 1804, he married Marie-Anne Lavoisier, the widow of the great French chemist Antoine Lavoisier, his American wife—the one he abandoned in America upon the outbreak of the American Revolution—having died since his emigration. Thompson separated from his second wife after 3 years, but he settled in Paris and continued his scientific work until his death on August 21, 1814. Thompson is buried in the small cemetery of Auteuil in Paris, just across from Adrien-Marie Legendre. Upon his death, his daughter from his first marriage, Sarah Thompson, inherited his title as Countess Rumford.