In most optical oxygen sensors, fluorescent quenching is used as the sensing principle. Intensity and lifetime are two known techniques that are employed to quantify the measured parameter. The lifetime technique has superior features such as little or no sensitivity to changes in the optical path or degradation of the film. We conducted an experiment to analyze both techniques with a platinum-porphyrin fluorescent film under different concentrations of oxygen. We demonstrate the inverse relationship between the lifetime of the fluorescence and the concentration of oxygen and the advantages the lifetime measurement has over measuring the intensity of the fluorescent film.