An apparatus for electrochemical determination of oxygen partial pressure in a glass melt, said apparatus comprising a pure platinum electrode, a Zirconium dioxide electrode including an internal platinum wire and an internal oxygen flush at a set pressure, a metal/metal oxide electrode selected from the group consisting of Mo/MoO.sub.2, W/WO.sub.2, Hf/HfO.sub.2, Nb/NbO and Ta/Ta.sub.2 O.sub.5 electrodes, means for immersing said platinum, Zirconium oxide and said metal/metal oxide electrodes in said glass melt, a sleeve surrounding a portion of said metal/metal oxide electrode not immersed in said glass melt and an inert gas atmosphere inside said sleeve around said portion, means for measuring an electrochemical potential across said Zirconium dioxide electrode and said metal/metal oxide electrode to calibrate said metal/metal oxide electrode, and means for measuring an electrochemical potential across said metal/metal oxide electrode and said pure platinum electrode to obtain a measured potential characteristic of an oxygen partial pressure in said glass melt,
- wherein said metal/metal oxide electrode consists of an electrode body made of a metal selected from the group consisting of Mo, W, Hf, Nb and Ta and alloys thereof and a layer of an oxide of said metal on said electrode body, said layer being formed by a method including immersing said electrode body in said glass melt.