Abstract A series of double-layered gas diffusion electrodes with two different electrocatalysts, i.e., Ag and pyrolyzed macrocycle mixture (PMM) were prepared in order to find out the maximum limiting current densities ( i L ) by varying the oxygen partial pressures in 6 M KOH and at 65 °C. As optimization of the active (catalyst) layer is important for better utilization of the catalytic reactions for oxygen reduction and thereby attainment of high current density, electrochemical measurements in half-cells were carried out to substantiate the current–thickness relationships. The thicknesses for both the active layers and diffusion layers were determined by using SEM. i L for an oxygen concentration simulating that of air was found to be 2.2 A cm −2 for the PMM with 0.51 mm and 1.6 A cm −2 for the Ag-based catalyst with 0.56 mm thicknesses of the active layer. An overlay of a mathematical model, describing the parameters for determination of i L , has also been inserted alongside the experimental values.