A composition comprising a matrix which, on pyrolysis, forms spinel, and an inorganic particulate filler having a hollow or a lamellar structure, wherein the matrix comprises a liquid pre-ceramic binder and at least one other component selected from a metal powder, a metal oxide powder and mixtures thereof, is provided. A heat resistant product which is obtainable by pyrolysing the composition is also provided. The resulting heat resistant product is capable of withstanding temperatures of greater than 1600° C., for instance up to and greater than 1850° C., and may be used in the form of a thermal barrier coating applied, or otherwise attached, to a surface of a substrate, which may, for example, form part of an aircraft, power-generating equipment, a furnace lining, a heat-exchanger, or a reactor.