Metal-oxide electrodes are used to determine the pH of solutions in various technological processes, but the mechanism of their action has not been sufficiently studied to date.

Evaluation of the stability of readings of a number of metal-oxide electrodes in measuring the pH of solutions was aimed at obtaining data for the selection of the most reliable electrode from the metals of the arsenic subgroup, as well as establishing the methodology of calibration of these electrodes. The electrochemical properties of arsenic, antimony and bismuth electrodes were tested by measuring potentials by the compensatory method. The arsenic electrode gives continuously increasing readings during the whole time under all the above test conditions. When solutions are stirred, it begins to dissolve noticeably, and in the presence of solid phase in the solution, it gradually breaks down. This makes the arsenic electrode unsuitable as an indicator electrode. Antimony electrode gives the most stable readings in solutions under stirring, especially with continuous mechanical cleaning of its surface. The bismuth electrode readings are also most stable in solutions when stirred in the presence of a solid phase.