As progress is made in the integration of structural and fire performance models for structural steel, one key component is a proper and accurate characterization of the thermophysical properties of the fire resistive materials (FRM). To predict the surface temperatures of the steel and its subsequent mechanical performance, an understanding of the energy transfer from the fire to the steel through the FRM is paramount. The four major thermophysical properties needed to model the thermal performance of the FRMs are: density, heat capacity, thermal conductivity, and enthalpy (of reactions and phase changes). Furthermore, these properties are needed as a function of temperature, from room temperature to temperatures greater than 1000 ºC. In this paper, various approaches for obtaining these data are reviewed and critiqued. It appears that a combination of experimental measurements and theoretical/modeling computations will provide the most robust and accurate characterization for these materials. While the mechanical integrity and adhesion properties of the FRMs as a function of temperature are also critical to successful performance during a fire exposure, they will not be considered in this initial study.