Regeneration of spent bleaching clay by heat treatment in a gas stream was performed in a thermogravimetric analysis system. Red color indices of peanut oils unbleached and bleached with fresh or regenerated clay were determined to calculate regeneration efficiency. The effects of processing parameters such as atmosphere, temperature, time, air flow rate, and amount of clay on the regeneration efficiency have been investigated. Weight losses, specific surface areas and pore volumes of clays were measured to clarify the mechanism of regeneration. Results indicate that regeneration in an air stream is slightly more efficient than that in stagnant air, and air is more efficient than nitrogen. The regeneration efficiency of clay is found to increase with temperature and time. However, it is reduced due to sintering of the clay. Air flow rate and amount of clay do not have any effect on regeneration efficiency.