Heat capacity for 1-butyl-3-methylimidazolium trifluoroacetate [bmim][CF3COO] and acetate [bmim][CH3COO] in the temperature range of (5 to 370) K has been measured by adiabatic calorimetry. Temperatures and enthalpies of phase transitions in [bmim][CF3COO] have been determined. Thermodynamic functions for the compounds in the condensed state have been calculated. Physicochemical properties for the studied ionic liquids and alkali acetate salts have been compared. The correlation scheme for estimation of C-p of ionic liquids in a range of (190 to 370) K has been developed. (C) 2007 Elsevier Ltd. All rights reserved.