Paper chromatography and radioisotopes were used to identify products formed during irradiation of D-glucose solutions in vacuo with Co6O gamma-radiation and 1-Mv electrons. By reference to yield-dose curves the following primary processes were recognized: (1) oxidation at C-1 to give gluconic acid; (2) attack at C-2 to give glucosone; (3) ring scission to yield two- and three-carbon aldehydic fragments; (4) dimerization of radicals of the type RCHOH as an initial step in the formation of polymeric material. The nature and yields of products indicate that primary abstraction are identical in 02 and in vacuo. The differing products must be attributed to differing secondary reactions of identical primary species. Abstraction by hydroxyl radicals cannot solely account for the whole of initial hexose degradation observed, which is the same in O2 and in vacuo ([long dash]G=3.5).