Mullite (3Al2O3.2SiO2) is commonly used phase for high temperature and thermal shock resistant applications in ceramic industry. In the present investigation, two different formation energies as microwave and conventional sources have been used to form mullite phase. Seydisehir alumina, gibbsite, kaolinite and quartz were used as starting materials. Seydisehir alumina and gibbsite raw materials have been transformed into α-alumina phase by heating at elevated temperature to improve mullite synthesis. The raw materials have been mixed according to stoichiometric ratio of 3Al2O3.2SiO2 and compacted as coin shaped test samples by uniaxial pressing. Test samples have been sintered using microwave and conventional energy sources with different duration and temperatures. The products have been characterized by SEM/EDS, XRD analysis.