The heat capacities of crystalline tetrabutylammonium iodide (TBAI) and tetrabutylammonium tetraphenylborate (TBATPhB) were determined over the temperature range 5-350K by adiabatic vacuum calorimetry, generally with an uncertainty of 0.2%. The experimental data were used to calculate the standard thermodynamic functions of TBAI and TBATPhB, namely, the heat capacity C-p(T), enthalpy H (T) - H (0), entropy S (T) and Gibbs function G (T) - H (0) at p = 0.1 MPa for the range from T-->0 to T=350 K. The standard entropy of formation Delta S-f TBAI and TBATPhB at T=298.15 K was also determined. Thermodynamic characteristics of fusion and solid-state transition were determined by DSC, their comparison with literature data were carry out: numerical values of enthalpies and entropies of transitions were discussed in dependence of compounds composition. (C) 2008 Elsevier B.V. All rights reserved.