Electrolyte solution suitable for maintaining polarographic dissolved oxygen probes and is ready to use in 30mL bottles. An oxygen probe is composed of a platinum electrode and a solid silver electrode. The concentrated potassium chloride solution is held in place over the electrode by a PTFE (polytetrafluorŒthylene) membrane (PHM0360). With polarographic technology, an external voltage is applied to the platinum cathode, silver anode, electrolyte solution and gas-permeable membrane to establish a current that is proportional to the concentration of oxygen in a solution.