The influence of temperature on the extraction of Pu(IV) into 30 vol.% tri-n-butyl phosphate in n-dodecane from acidic nitrate solutions has been investigated at temperatures ranging from T=(294 to 313) K. Temperature was found to decrease the distribution of Pu(IV). Three species of plutonium were considered present in the aqueous solution: Pu4+, [image omitted], and [image omitted]. The enthalpy and entropy of the extraction, calculated using Van't Hoff plots, are -60.4 +/- 3.34kJ center dot mol-1 and -120 +/- 10.6J center dot mol-1 center dot K-1, respectively.