Using the solution-reaction isoperibol calorimeter, molar enthalpies of solution in water, Delta H-sol(m), for ionic liquid [C(4)mim][OAc] with different molalities were measured in the temperature range of (288.15-308.15 +/- 0.01) K with an interval of 5 K. According to Archer's method or Pitzer's electrolyte solution theory, the values of the standard molar enthalpies of solution, Delta H-sol(m)(-) the apparent relative molar enthalpy L-Phi, and the parameters beta((0)L)(MX), beta((1)L)(MX) were determined for [C(4)mim][OAc]. According to Krossing's theory of lattice energy, the hydration enthalpy of cation and anion in infinite dilution aqueous [C(4)mim][OAc] were calculated, (Delta H+ + AH(-)) = -531.6 kJ mol(-1), at 298.15 K. A linear relationship was found by plotting the experimental values of Delta H-sol(m) against (T - 298.15) K. The standard molar heat capacity of solution, LCprn =339 J K-1 mol-1 was obtained from the slope of the regression line, and the specific heat capacity of solution, Delta C-p((-)) =1.70 Jg(-1) K-1, was also determined for [C(4)mim][OAc]. (C) 2013 Published by Elsevier B.V.