In the present research, the temperature dependence of the heat capacity C-p,m(o) = f(T) of pentaphenylantimony Ph5Sb has been measured between T = (6 and 350) K in the precision adiabatic vacuum calorimeter and from T = (327 to 415) K in the differential scanning calorimeter and reported for the first time. The melting of the sample has been observed within the above temperature range. The melting was accompanied by partial compound decomposition. The experimental results have been used to calculate the standard (p(o) = 0.1 MPa) thermodynamic functions C-p,m(o)/R, Delta H-T(0)m(o)/RT, Delta S-T(0)m(o)/R, and Phi(o)(m)/R = Delta S-T(0)m(o)/R - Delta H-T(0)m(o)/RT (where R is the universal gas constant) of crystalline Ph5Sb over the range from T -> 0 K to 400 K. The energy of combustion of the compound under study has been determined in the isothermal combustion calorimeter with a stationary bomb. The standard thermodynamic functions of crystalline Ph5Sb formation at T = 298.15 K have been calculated. (C) 2008 Elsevier Ltd. All rights reserved.