The electron transport coefficients, the drift velocity W, the product of the gas number density and the longitudinal diffusion coefficient and the ratio of the longitudinal diffusion coefficient to the electron mobility of electrons were measured in pure oxygen over the range 1.7-350 Td and in two oxygen-argon mixtures (with 1.01% and 4.994% oxygen) from about 0.03 to 3 Td by using a double-shutter electron drift tube with a variable drift distance. The present and were the first measured over almost the entire part of the present range. The drift velocities in the mixtures exhibited a typical negative differential conductivity and they will be important in testing existing vibrational excitation cross sections for the oxygen molecule.