A wash-coat (16) for use as a support for an active catalyst species (18) and a catalytic combustor component (10) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al2O3-0-3 wt % La2O3) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO2), zirconia silicate (2-30 wt % ZrSiO4), neodymium oxide (0-4 wt %), titania (Al2O3-3-40% TiO2) or alumina-based magnesium aluminate spinel (Al2O3-25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.