Absorption spectra of gas-phase molecular oxygen and zero air at temperatures of 223 and 283 K have been measured in the laboratory using a coolable multipass-optics gas cell and Fourier transform spectroscopy in the wavelength range 455 to 830 nm (12,000--22,000 cm-1). Net absorption cross sections of the O2 A-, B-, and &ggr;-bands at <0.002 nm spectral resolution, and pressures of 100 and 1000 hPa zero air have been determined. Binary absorption cross sections of the collision-induced O4 bands at <0.18 nm spectral resolution and a pressure of 1000 hPa pure oxygen have been determined, with corrections for the O2 &ggr;-band absorption. Calculated integrated absorption intensities and, for the O2 A- and B-bands, effective Einstein A-coefficients are compared with previous literature values. ¿ 1998 American Geophysical Union