Heat capacities and enthalpies of phase transitions for a series of 1-alkyl-3-methylimidazolium bromide ionic liquids have been measured by adiabatic calorimetry. Thermodynamic properties of the compounds were calculated in the temperature range of (5 to 370) K. Water was found to have an additive contribution to the heat capacities Of [C(4)mim]Br in the liquid state above T-fus and in the solid state below 160 K at w(H2O) <= 5 (.) 10(-3). (c) 2006 Elsevier Ltd. All rights reserved.