Biomorphic silicon carbide (bioSiC), a novel porous ceramic derived from natural wood precursors, has potential applicability at high temperatures, particularly when rapid temperature changes occur. The thermal conductivity of bioSiC from five different precursors was experimentally determined using flash diffusivity and specific heat measurements at temperatures ranging from room temperature to 1100°C. The results were compared with values obtained from object‐oriented finite‐element analysis (OOF). OOF was also used to model and understand the heat‐flow paths through the complex bioSiC microstructures.