To determine the mechanism of the radiation-induced reactions of cellulose and to evaluate these chemical alterations of the cellulose molecule with relation to the production of new cotton products, the specific chemical nature of the oxidized groups formed must be known. Even though previous work indicated that only small differences in properties were produced, the atmosphere under which the irradiation was carried out is very important in respect to the exact chemical nature of the groups produced. Investigations of the specific nature of the groups formed on cotton cellulose in an atmosphere of oxygen at a gamma radiation dose of 10/sup 8/ r are reported. The penetrating power of gamma -rays, and probably most other kinds of high energy radiation, makes the oxidative degradation of the cellulose molecule unique when compared to ordinary chemical oxidations. The ionizations induced in cellulose are not hindered by the crystalline-amorphous nature of the cellulose structure. The gamma irradiation of cellulose produces chain cleavage, reducing groups and acid groups. The chain cleavage ratio for this work was found to be 19: 0.5: 1 as compared to 20: 1: 1 found by Arthur and Blouin. The distribution of acid groups between the various fractions of themore » irradiated cellulose indicated that acid group production was principally a chain-end effect and that one acid group was produced per every two chains formed. The data suggested that activation of the C/sub 2/, C/sub 3/, C/sub 5/, and C/sub 6/ positions of the polymer caused reducing group formation with evolution of hydrogen and without chain cleavage. The carbon monoxide and carbon dioxide evolved in the irradiation are considered to be secondary degradation products from aldehydes and/or ketones for CO and decarboxylation of carboxyl groups in the case of CO/sub 2/. (B.O.G.)« less