High-surface area (25m 2 g - 1 ) Mn-doped barium hexa-aluminates with compositions BaMnAl 1 1 O 1 9 and BaMn 2 Al 1 0 O 1 9 were prepared by a combination of hydrothermal precipitation-calcination route. The precursors of the above two compounds were obtained by hydrolyzing a mixture of aqueous solutions of Ba, Al, and Mn at 180 o C for 1h in the presence of urea. The analysis of the hydrothermally prepared samples showed the presence of carbonate and/or hydroxide phases of Ba and Mn and boehmite. Barium mono-aluminate (BaAl 2 O 4 ), Ba-β I I -Al 2 O 3 , γ-Al 2 O 3 , and a small fraction of MnO 2 were observed after calcination of these hydrothermally prepared precursors at 1200 o C. A mixture of Ba-β I -Al 2 O 3 and Ba-β I I -Al 2 O 3 phases were found after calcination at 1400 o C for 2h with no other oxide phases of Ba, Al or Mn.