The first codicil, an amendment to Napoleon's will, bears his famous words: "I want my ashes to rest on the banks of the Seine, among the French people whom I loved so much."
The second document spells out the bequeathal of money, jewelery, books and weapons to his many supporters and to his "good and dear mother."
The codicils are expected to fetch between 80,000 and 120,000 euros ($109,000 and $163,000), TheLocal.fr said.
The auction house Drouot is in charge of the sale. Information on the present owner was not released.
The codicils are the only two remaining known portions of Napoleon's will still in private hands. The diminutive emperor entrusted his will and two copies to an aide while he was held in a British prison on the South Atlantic island St. Helena for the final six years of his life.