Mn-substituted Ba-La-hexaaluminate rod-like nanoparticles with high surface area in the range between 45 and 73 m2/g have been prepared using the alumina sol as the (NH4)2CO3 co-precipitation precursor and the supercritical drying (SCD) method. The properties and microstructures of the catalysts are determined by the ion mobility at high calcination temperature. The nature of the large cation in the mirror plane can affect the Mn2+/Mn3+ redox process. The Ba0.2La0.8MnAl11O19−α catalyst possesses the highest catalytic activity owing to the excellent performance of activating oxygen.