The ultraviolet absorption cross sections of hydrogren peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296¿K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3¿10-5 sec -1.