Using the solution-reaction isoperibol calorimeter, molar enthalpies of solution in water, Delta H-sol(m), for ionic liquid [C(6)mim][OAc] with different molalities were measured in the temperature range from (288.15 to 308.15 +/- 0.01) K with an interval of 5 K. According to Archer's method, the values of the standard molar enthalpies of solution, Delta H-sol(m)theta were obtained for [C(6)mim][OAc], respectively. According to Glasser's theory of lattice energy, the hydration enthalpy of cation and anion in infinite dilution aqueous [C(6)mim][OAc] was calculated, (Delta H+ + Delta H-)= -598 kJ mol(-1), at 298.15 K. The hydration enthalpy of the cation, Delta H+ ([C(6)mim](+))= -173 kJ mol(-1), was determined. In comparison with hydration enthalpy of [C(2)mim](+), the hydration enthalpy of [C(6)mim](+) is a little bit weaker. A linear relationship was found by plotting the experimental values of Delta H-sol(m)theta against (T-298.15) K. The standard molar heat capacity of solution, Delta C-p,m(theta) = 313J K-1 mol(-1), was obtained from the slope of the regression line, the specific heat capacity of solution, Delta C-p(theta) = 1.38J g(-1) K-1, and the apparent relative molar heat capacity, C-Phi(p), were also calculated for [C(6)mim][OAc]. (C) 2014 Elsevier B.V. All rights reserved.