In the present work temperature dependence of heat capacity of vitamin B-12 (cyanocobalamin) has been measured for the first time in the range from 6 to 343 K by precision adiabatic vacuum calorimetry. Based on the experimental data, the thermodynamic functions of the vitamin B-12, 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 thermal stability of cyanocobalamin was also studied by differential scanning calorimetry. (C) 2014 Elsevier B.V. All rights reserved.