Extraction of uranium with bis-(2-ethylhexyl) phosphonic acid (PC-88A) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex-272) was studied in several imidazolium-based room-temperature ionic liquids (RTILs), C(n)mimX (where n = 4, 6, 8 and X = PF6 and Tf2N). The extraction kinetics was slow and about 0.5-1 h equilibration time was required for most of the extraction systems, except in C(8)mimPF(6), where 2 h and 4 h were required to reach the equilibrium values for PC-88A and Cyanex-272, respectively. The extraction of UO22+ ion by the two ligands was significantly affected by the nature and the composition of the RTILs.