A novel amino acid ionic liquid [C(4)mim][Gly] (1-butyl-3-methylimidazolium glycine) was prepared by a neutralization method. The molar enthalpies of dilution, Delta H-D(m)(m(i)-> m(f)), of aqueous [C(4)mim][Gly] at various molalities were measured at (298.15 +/- 0.01) K. The values of the apparent relative molar enthalpy, L-phi, were calculated by using both the extended Debye-Huckel equation and the Pitzer equation, which were in good agreement within experimental error. In terms of L-phi, the molar enthalpies of solution of [C(4)mim][Gly], Delta H-s(m), at various molalities were estimated. The estimated values of Delta H-s(m) were consistent with the experimental values previously obtained.