An analysis was given on the response time of the capillary type oxygen sensor. There are two main influencing processes to be taken into consideeration, namely, the charging of the double layer and the readjusting of the oxyen concentration inside the gas chamber between the capillary and the catalytic layer of the air electrode. The first process is determined by the double layer capacity of the air electrode and the load resistance, while the second by the volume of the gas chamber and the electrode reaction rate constant which is a function of the electrcde potential. The theoretical approach compared favorably with the experiments. Several principles were proposed for shortening the response time.