Oxygen-permeable polyurethane ionomers with dimethyldimethoxysilane or dimethyldimethoxysilane have been successfully synthesized at our lab, and their ionomer structures have been proven by infrared spectra. In our previous paper,(1) it was found that the amount of oxygen permeated through the film made by a dimethyldichlorosilane polyurethane ionomer increased with increasing the concentration of dimethyldichlorosilane. Presently, our experimental results also indicate that use of dimethyldimethoxysilane or dimethyldiethoxysilane in preparing polyurethane ionomers does substantially raise the amount of oxygen diffusing into the films made by these ionomers. These results suggest that use of dimethyldichlorosilane, dimethyldimethoxysilane, or dimethyldiethoxysilane, with strong hydrophilic property, in making polyurethane ionomer will give better oxygen permeability of siloxane-based polyurethane ionomers. It is interesting to point out that both tensile strength and the elongation of a siloxane-based polyurethane ionomer film become weaker as the concentration of dimethyldimethoxysilane or dimethyldiethoxysilane increases. This may be the result of intramolecular interaction of ionomer molecules, coupled with the reduction of the formation of hydrogen bonding between ionomer-ionomer molecules and between ionomer-water molecules.