Feasible study of whole micro-SOFC system using methanol fuel for small power sources in mobile electronic devices was performed. These new power sources are required to achieve heat-self-sustainability and thermal consistency due to its high operating temperature. To satisfy the requirements, energy flow in the system consists of insulation packages stored micro-SOFC was calculated based on thermodynamics, and achievement was evaluated by changing the thickness of insulator. Calculation results confirmed that the requirements were satisfied with small size packages, could be stored in mobile electronic devices. In addition, volumetric energy density of the system was higher than that of Li-ion batteries. Therefore, it was confirmed that the application of micro-SOFC as a new power sources for mobile electronic devices had advantage compared to Li-ion batteries.