A 150-mm LDPE film contg. only small amounts of an antioxidant, was electron-irradiated (25, 50, 100, 250, and 500 kGy) at room temp. in air and studied by XPS in layers 0.6, 1.9, and 3.7 nm deep. Oxygen O(1s) (2-4 binding forms) in the topmost layer, 0.6 nm thick, rose to 7.8 and 12% in direct relation to dose over 25-250 (at 0.3%/10 kGy) and 250500 kGy. It was desorbed primarily from this layer. The layers examined contained only C, H and O. The deepest layer was least oxidized. The various O radicals formed made the resulting polar groups difficult to identify.