AbstractAb initiomolecular orbital theory was used to compute entropies, heat capacities and other thermochemical properties for a new organosilicon compound H2SiNaF in the temperature range 300–1500 K. There is currently no information of this kind available about this compound. On the basis of the calculated heat capacities, we have fitted the temperature‐dependent functions for heat capacities to the forms (a+bT+cT2) and (a'+b'T+c'T−2) in the range 300–1500 K. Furthermore, we calculated the equilibrium constants of conversions among the four configurations of this compound. Thus, a new way of determining thermodynamic data theoretically can be derived and is expected to be esta