High Temperature Air/Steam Gasification (HTAG) is a process in which a highly preheated air/steam is utilized as the oxidizer. The HTAG process follows the developments in the High Temperature Air Combustion (HiTAC), which has shown to be superior in energy saving and pollution reduction compared to the conventional combustion technology. The preheated oxidizer provides additional energy into the gasification process that enhances thermal decomposition of the gasified solid feedstock. Consequently, the HTAG increases both the calorific value of the producer gas, and the cold gasification efficiency. In this work, the advantages of the HTAG processes is presented by considering performance influencing parameters that include materials quality, oxidizer type, equivalence ratio (ER), gasification temperature, and bed additives.