This study investigates the phase compositions in gelcast dense alumina and porous alumina that were sintered in an inert atmosphere. Both materials were gelcasted using identical slurry composition except for adding surfactant to slurry intended for porous shaping. The resulting gelcasted samples were dried and then sintered in argon gas at 1700oC. The X-ray photoelectron analysis was used for identifying the phase compositions in sintered samples, which was supported with TG/DTA and electrical measurements. Results showed that, in addition to alumina and carbon phases, the dense sample yielded Al4C3 and Al, while porous sample yielded aluminum oxycarbides. The formation of these phases reduced the carbon content through different chemical reactions to a limited extent because they formed a protective layer on alumina grains, which prevented the direct contact between alumina and carbon. Subsequent measured electrical resistivities of dense and porous alumina were, respectively, 0.20 and 0.32 ,-cm, indicating that the carbon networks are preserved in both materials.