He died in 1870 of a pulmonary congestion in his hotel on rue Saint-Dominique in Paris. Dying without legitimate issue, his title of Prince of San Donato passed to his nephew Pavel Pavlovitch Demidov.
Cimetière du Père Lachaise. Plot # Family Mausoleum
He is married to Mathilde Laetitia Wilhelmine Bonaparte.
They got married on November 1, 1840 at Florence, Firenze, Toscana, Italy, he was 27 years old.Source 2