Determination of the thermal conductivity coefficient (Kc) of solid materials at high temperatures. Analyses are carried out at at least three temperatures (between 400oC e 1000oC) by the calorimetric method, based on the procedures described by the ASTM C201 – 93 standard. The results allow evaluating the thermal insulation power of dense or insulating refractories, in addition to other materials used in the thermal insulation of industrial installations subjected to high temperatures.