The present paper demonstrates that room temperature ionic liquids (RTIL) added at 1-5 wt% to a diphenyl (dibutyl) carbamoylmethylphosphine oxide (Ph ₂Bu₂) solution increase the extraction coefficients of americium from nitric acid by more than two orders of magnitude. Moreover, the use of the RTIL - 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide makes the extraction possible even from 8 M HNO₃. This is an important attribute of such extraction system from the point of its possible application for radiochemical analysis of technological samples and environmental solutions, since many methods are based on transferring the solid samples into an 8 M HNO₃ solution. The extraction data obtained revealed that three Ph₂Bu₂ ligands are included into the coordination sphere of americium, two of which represent a compound with the nitrate anion and one with the RTIL anion.