The authors present conclusive evidence to illustrate that reversible binding of O2 to transition-metal O2 carriers can be utilized to facilitate transport of O2 through a solid membrane when such complexes are incorporated into the membrane. The key experiment to establish this concept involves the proper selection of a blank film. The polystyrene-supported CoSDPT type complexes and blanks consisting of nickel(II) derivatives are ideal for demonstrating facilitated transport because of their structural similarity. We also present a procedure for evaluating permeation data, which should find widespread use in this area since it eliminates imperfections that can exist in test and blank membranes. A transport mechanism is discussed in light of these results.