Boehmite sol was prepared by hot water hydrolysis of aluminum iso-propoxide using nitric acid as the catalyst. Calcium nitrate to yield 0-20 vol% calcia was added to the boehmite sol. The boehmite with additives was calcined at 600° C for 3 h. The calcined powder was milled at 230 rpm for 6 h and particle size was measured using Laser particle size analyzer. The powder samples were calcined at 1600° C for 3 h and the formation of calcium hexaaluminate was discussed using phase diagram, transmission electron microscope, energy dispersive spectra, and X-ray diffraction spectra. The powder samples calcined at 600° C for 3 h were compacted into cylindrical pellets and sintered at temperatures ranging from 1400° to 1600° C for 6 h and the formation of hexaaluminate (platelike) grains were confirmed using Scanning electron microscope and optical microscopy.