Macroporous cordierite 95 x 76-mm cylinders were impregnated 1 h at 55-65degreesC to absorb up to 22% (cylinder wt. basis) of aq. 23% Mn(OAc)(2) and aq.11.5% Mn(NO3)(2) contg. 0.1% Ca(OAc)(2) as promoter, dried at 120degreesC and heated 1 h at 450degreesC to yield ca. 5% of MnO2 as a catalytically active species in the cylinder. The Mn nitrate decompd. over 150-250degreesC and Mn acetate over 260-270degreesC to release NO. and CO --> CO2, resp. In test combustions of (i) acetone, (ii) toluene, and (ill) hexane, the present Mn catalyst was (i) more, (H) less and (ill) equally active as compared with a monolithic Pt catalyst. The fresh Mn catalyst acquired stable activity in 50 h and retained it for 500 h in the course of burning up of acetone and hexane.