In the present work temperature dependence of heat capacity of vitamin B-3 (nicotinic acid) has been measured for the first time in the range from 5 to 346 K by precision adiabatic vacuum calorimetry. Based on the experimental data, the thermodynamic functions of the vitamin B-3, namely, the heat capacity, enthalpy H degrees(T) - H degrees(0), entropy S degrees(T) - S degrees(0) and Gibbs function G degrees(T) - H degrees(0) have been determined for the range from T -> 0 to 343 K. The value of the fractal dimension D in the function of multifractal generalization of Debye's theory of the heat capacity of solids was estimated and the character of heterodynamics of structure was detected. The thermodynamic parameters Delta S-f degrees, Delta(f)G degrees at T=298.15 K and p = 0.1 MPa have been calculated. The thermodynamic analysis of reactions involving nicotinic acid was made. The low-temperature X-ray diffraction was used for the determination of coefficients of thermal expansion. (C) 2015 Elsevier B.V. All rights reserved.