Reports on freeze-cast ceramic materials frequently focus on the study of the organized macroporosity and the properties of the materials. This study aims to describe the microstructure evolution of freeze-cast alumina during the sintering process, analyzing grain growth, densification, pore elimination and crystal structure at different sintering temperatures (1300-1500 °C). Aqueous suspensions with 20 vol% alumina were freeze-cast in liquid N2 and sintered. The microstructure was analyzed by stereological analysis, N2 adsorption and X-ray diffraction. Grain sizes varied within 237-500 nm, and the intergranular porosity decreased from 8.8% at 1300 °C to 1.4% at 1500 °C. N2 isotherm analysis revealed pore shrinking from the region of macro and mesopores (20-80 nm), to smaller residual mesopores (3.7-15 nm) at temperatures above 1400 °C. Rietveld refinement of the XRD diffractograms confirmed increased crystallite size and decreased lattice strain at higher sintering temperatures. This comprehensive description of microstructural evolution of the freeze-cast alumina contributes to understanding the sintering of highly porous ceramics produced via freeze-casting. freezecast freeze cast process growth densification 13001500 (1300-150 C . °C) 2 vol N sintered Xray X ray diffraction 237500 237 500 237-50 nm 88 8 8.8 130 14 1 4 1.4 150 2080 80 (20-8 , 3.715 3715 3.7 15 3 7 (3.7-1 140 freezecasting. freezecasting casting. casting freeze-casting 1300150 (1300-15 23750 23 50 237-5 8. 13 1. 208 (20- 715 3.71 371 37 3. (3.7- 130015 (1300-1 2375 5 237- (20 71 (3.7 13001 (1300- (2 (3. (1300 ( (3 (130 (13 (1