The feasibility of extracting uranium from natural ores has been studied, using supercritical CO2 and either commercial extractants (PC88A, Cyanex 301 (R)) or an amidophosphonate molecule (named DEHCNPB). The impact of the process parameters has been evaluated. The uranium extraction yield was optimal at the lowest temperature (40 degrees C) and highest pressure (25 MPa) tested here. For a given CO2 flow rate, a compromise should be established between the amounts of extractant, acid and oxidant used. Uranium was successfully extracted directly from natural ore using DEHCNPB with a good selectivity over metal impurities such as iron, titanium and vanadium and yields up to 97%. Moreover, using Fe-2(SO4)(3) as an oxidant allows to minimize the water usage of the process. The mechanism of extraction using supercritical CO2 has been elucidated thanks to electrospray ionization mass spectrometry. (C) 2017 Elsevier B.V. All rights reserved.