In this work, the equilibrium distribution of (E)-butenedioic acid (fumaric acid) between water and tridodecylamine (TDDA) or tributylamine (TBA) was carried out at 298 K. The organic phase was prepared using both TDDA and TBA in three nontoxic diluents (canola oil, sesame oil, and almond oil). The batch equilibrium experimental data are presented by calculation of the loading factor (Z), extraction efficiency (E), and distribution coefficient (K-D). The highest extraction efficiencies of 92.59 % and 92.50 % with values of KD equal to 12.50 and 12.40 were obtained with 0.789 mol center dot kg1 TDDA in canola oil and 2.080 mol.kg(1) TBA in canola oil. The extraction abilities of TDDA and TBA in different nontoxic natural diluents in terms of K-D and E were found to be in the order of canola oil > almond oil > sesame oil. Partition coefficients (P = 0.3819, 0.4739, and 0.7535) and dimerization constants (D = 83.64, 50.28, and 43.51) were calculated according to physical extraction for sesame oil, almond oil, and canola oil, respectively.