This research is to investigate transportation of oxygen and nitrogen through natural rubber membrane, vulcanized rubber membrane and vulcanized rubber membrane mixed with naphthalene. The hypothesis is that gases permeate through pores formed during membrane preparation. The influences of pressure and temperature on permeability and selectivity have been studied. Results have shown that the pressure drop does not affect permeability and selectivity of membranes but the increase of temperature causes the increase of gas permeability and a slight decrease of selectivity. Naphthalene has been added to create small pores in the membrane. It appeared that at 10 phr of naphthalene the permeability IS maximum but the selectivity of O2 / N2 was not affected by the quantity of naphthalene with an average value around 2 - 3. The mechanical properties of membrane, i.e. tensile strength and modulus of vulcanized rubber membrane stay nearly the same and these properties are 3 times higher than that of unvulcanized rubber.