Thermodynamic properties of 2-(1'-hydroxycyclohexyl)cyclohexanone (ketol) are reported. The investigated compound is a byproduct from the caprolactam manufacture. The heat capacity of ketol was measured by vacuum adiabatic calorimetry (T = 5 K to T = 310 K) and by differential scanning calorimetry (T = 294 K to T = 370 K). The fusion temperature T-fus = 306.75 K and the mole fraction of the ketol sample (x = 0.9982) were found by fractional melting analysis. The molar enthalpy of fusion Delta(fus)H(m)(0) = (20.81 +/- 0.02) kJ(.)mol(-1) was determined in the adiabatic calorimeter. The standard molar thermodynamic functions of ketol in the condensed state were obtained with the use of these calorimetric measurements. The standard molar enthalpy of combustion of ketol Delta(c)H(m)(0)(cr, 298.15 K) = -(6963.0 +/- 1.8) kJ(.)mol(-1) was found by bomb calorimetry, and the standard molar enthalpy of formation Delta(f)H(m)(0)(cr, 298.15 K) = -(597.6 +/- 2.4) kJ(.)mol(-1) was derived. The equilibrium of dimerization of cyclohexanone with ketol formation was investigated in the temperature range 294 K to 367 K. The equilibrium constants (K-a) were obtained at five temperatures, and the enthalpy of the reaction at the average temperature Delta(r)H(m)(330.5 K) = -(34.4 +/- 3.3) kJ(.)mol(-1) was derived.