Physical property data of mixtures of ionic liquids with other liquids and gases are vital to evaluating them as potential reaction and separation solvents for a wide variety of industrial applications. In particular, heat of mixing data and heat capacities are needed to evaluate heating and cooling requirements, as well as assessing the usefulness of ionic liquids for absorption refrigeration. Here, we are interested in mixtures of ionic liquids (1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium trifluoroacetate, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate) with water as a function of temperature and composition. The enthalpies of solution of the ionic liquids in water were obtained by calorimetry, using Setaram Micro DSCIII and C80 calorimeters. The heat capacity measurements were performed with a Mettler Toledo differential scanning calorimeter (model DSC882^e). The measurements were performed at atmospheric pressure including temperatures from 25 to 75 ^oC and the entire range of mole fraction. The anion effects were investigated by maintaining a constant cation and varying the anion. The data are correlated and analyzed with a Redlich-Kister type model. These mixtures show relatively small deviations from ideality, perhaps due to the balance in the strength of the like and unlike hydrogen-bonding interactions compared to the coulombic forces.