Thermal degradation of boards made from wood particles mixed with gypsum and gypsum-cement was determined in air and nitrogen by thermogravimetric analysis. The pure constituents of the boards (wood particles, gypsum, and Portland cement) were characterized separately. The thermal conductivity of the boards was determined using a heat flowmeter apparatus. Commercial gypsum board was used as a control for all the tests performed. Commercial gypsum board, pure gypsum, pure Portland cement, and gypsum-cement mixture showed mass losses between 18 and 22% at 800°C. Conversely, the wood particles were very sensitive to heat in the presence of air. In general, gypsum-cement particleboard exhibited better resistance to thermal degradation than gypsum particleboard, but it has the highest thermal conductivity as a result of its higher density. Thermal conductivity was shown to be strongly dependent on board density