Abstract: The distribution data for U(Ⅵ) from 0.25-5 mol·L~(-1) nitric acid media with 1--40 V% DHDECMP (dihexyl N,N-diethyl carbamoylmethyl phosphonate) in DEB (diethyl benzene) were determined in the temperature range 288--343 K. From the variation of the distribution ratios with temperature the enthalpy changes associated with the extraction were evaluated. Using extrapolation technique the thermodynamic value of the enthalpy (ΔH°_t) for zero ionic strength was obtained to be -27.5 kJ·mol~(-1). The thermodynamic equilibrium constant (K_t), free energy (ΔG°) and entropy changes (ΔS°) were calculated at 25 ℃ to be 1.15×10~3, -17.5 kJ·mol~(-1) and -33.5 J·mol~(-1)·K~(-1), respectively.