The present invention relates to a compact, concentric auto thermal hydrogen/syngas generator for production of hydrogen/syngas without any external heating. Further, the auto thermal hydrogen/syngas generator of the present invention involves combination of reactions such as partial oxidation, steam reforming, dry reforming, auto thermal reforming, dry autothermal reforming, water gas shift, preferential oxidation or methanation that takes place without external heating, for converting air, steam and fuel into a reformate mainly containing CO, CO2, N2, CH4 and H2O which is subsequently converted to hydrogen/syngas as a feed for fuel cell or syngas applications.