Electrochemical splitting of water, using solid oxide electrolysis cells (SOEC), offers an economic and efficient pathway for large-scale hydrogen production that not only utilizes and integrates renewable energy but also allows for both distributed and centralized hydrogen production to accelerate and enable hydrogen infrastructure for mobility. In this technical contribution, two types of electrochemical systems using conventional oxygen ion conducting (O-SOEC) and newly developed proton conducting (P-SEOC) will be compared. The advantages and disadvantages of each technology in terms of hydrogen purity, electrochemical performance, and stability (structural and electrochemical) will be analyzed. Experimental results from initial 100-hour tests will be presented and discussed. The observations on dopant exsolution, solid-solid (electrode/electrolyte interface) and solid-gas (electrode-H₂O, O₂, and H₂) interactions will be presented. Electrode composition, structure, and morphology changes and their roles on electrochemical performance and electrode stability in oxidizing (O₂) and reducing (H₂) atmospheres will be discussed