An electrochemical cell which includes a solid electrolyte body and a plurality of electrodes formed on the solid electrolyte body, for determining the concentration of a component contained in a measurement gas. The electrodes include at least one porous electrode exposed to the measurement gas. The method includes a step of preparing an unfired electrode material for the porous electrode or electrodes, which includes an inorganic compound which produces a gas at an elevated temperature, and an electrically conductive material. The unfired electrode material is applied to the solid electrolyte body to form an unfired electrode layer or layers corresponding to the porous electrode or electrodes. The formed unfired electrode layer or layers is/are heated to a temperature higher than the above-indicated elevated temperature, to form the porous electrode or electrodes.