In this paper we calculated optical transmittance of the In-Plane Switching (IPS) liquid crystal (LC) cell with respect to temperature. By considering temperature energy term in the Gibb's free energy, we could achieve the temperature parameters that need to calculate the temperature dependence on the electro-optic characteristics. The calculated temperature parameters permit us to calculate scalar order parameter S with respect to temperature, so that finally we could calculate the optical transmittance of the IPS LC cell as a function of temperature.