A polarographic oxygen detection cell of the type having concentric coplanar electrodes. The cell achieves more consistent and predictable operation by using electrode insulators to prevent electrochemical reaction between the areas of high charge density on the cathode and anode conduction disk and those portions of the electrolyte in which increased ion concentration has been attracted by this high charge density, and using the OH.sup.- based electrolyte and a carbon anode so that the reaction at the anode produces gas which can be bled off to avoid altering the composition of the anode or electrolyte.