Vapor pressure data and sublimation enthalpies of organometallic compounds that were measured by thermogravimetry and the application of Langmuir's equation are reported. Herein is a detailed experimental procedure that is applied to nickelocene and cobaltocene. The accuracy and uncertainty for the experimental nickelocene sublimation enthalpy show that the measurement reliability is comparable to the direct calorimetric data that have already been reported for this organometallic compound. Furthermore, the melting temperature and enthalpy as well as the crystal-phase heat capacities between (295 to 420) K for cobaltocene and nickelocene were calorimetrically measured by differential scanning calorimetry (DSC), whereas the gas-phase heat capacities for these metallocenes were theoretically estimated using density functional theory (DFT) calculations.