In this study, the aim was to investigate the possibility of obtaining porous ceramics using the sacrificial phase method, by using waste graphite and sintering the samples in a hybrid microwave oven. Waste graphite was used because it is readily available, burns at a lower temperature than the ceramic sintering temperature, and is environmentally cost-effective. The samples were microwave-sintered since it is an unconventional process that is increasingly being used, and the material properties before and after the sintering process were compared. Suspensions containing 60 wt.% of Al2O3 powder with varying weight percentages of waste graphite (0%, 1%, 5%, and 10%), dispersant, and binder were prepared. The green bodies were obtained by pouring the suspension into plaster molds after homogenization in a planetary ball mill. In order to compare the properties before and after sintering, the dimensions and mass of the green bodies were measured. Subsequently, sintering was performed in a hybrid microwave oven at 1600 °C. The sintered samples were analyzed using a scanning electron microscope (SEM) to examine the microstructure, followed by measurements of mass and density change, porosity, and shrinkage. Based on the obtained results presented in tables and figures at the end of the study, conclusions were drawn regarding the influence of waste graphite on the properties of porous ceramics sintered in a hybrid microwave oven.