Abstract: The cardiac pacer disclosed herein is of the type in which pulse-generating circuitry is energized by an electro-chemical cell of a type which gives off hydrogen during depletion of the cell, e.g. a mercury battery. A hermetically sealed case is provided for enclosing both the circuitry and the electro-chemical cell to protect them from body fluids, the case having at least one feed-through terminal for coupling pulses generated by the circuitry to a lead adapted for contacting a patient's heart. A getter is disposed within the case consisting essentially of a solid mass of palladium metal having a thin layer of palladium oxide formed on the outer surface thereof. A preferred method of forming the palladium oxide is by anodizing the mass of palladium metal in a sulphuric acid bath.