Hexaaluminate powder has been synthesized with the impregnation of La(NO 3 ) 3 and Mn(NO 3 ) 2 onto γ-Al 2 O 3 and subsequent calcination at 1400 o C. The hexaaluminate powder was formed into monolithic honeycomb of 200 cpi. The results of X-ray diffraction of the samples showed that the powder and the monoliths consisted of LaAl 1 1 O 1 9 and LaAlO 3 phases. The BET surface area of the manganese substituted powder and honeycomb decreased dramatically to ~13 m 2 g - 1 at 1200 o C. Further heat treatments up to 1400 o C did not cause a significant reduction of the surface area, ~7 m 2 g - 1 for both sample. The bending strength of the monolithic honeycomb decreased significantly when the temperature jumped about 300 o C as a thermal shock was applied. The manganese inserted as a catalyzing component in the magnetoplumbite structure allowed lean methane combustion, 1% over the honeycomb heated at 1400 o C, to start at 480 o C, comparable to that of the corresponding powder.