Thermodynamic functions, Cj, Sp, (Ha -H i ) /7, -( -H:)/T, have been calculated for Freon 113 in the ideal gas state at 1 atrn. pressure. The internal rotational contribution has been treated in two ways: by the Lielmezs-Bondi approximate method and with Pitzer-Gwinn's computed value of internal rotational partition function. The agreement between the computed results and the few available experimental vapor state heat capacity values, is satisfactory.