Oxygen permeation through solid polymer membranes is measured electrochemically by detecting the reduction current of the permeated oxygen on a carbon electrode. This method is especially effective for the measurement of facilitated oxygen transport through polymer membranes containing oxygen-specific fixed carriers, such as cobaltporphyrins, because of its high sensitivity to low permeated or downstream oxygen pressure and because it is an equal pressure process suitable for the measurement of brittle membranes with high contents of carrier molecule.