The microelectrode holder-half-cells couple fluid-filled glass micropipettes to high input impedance amplifiers. A silver wire molded into the holder body provides stable potential. Electrical connection is made via male 2 mm pins. Pipettes are held with screw-caps or rubber gaskets (without caps). Filling microelectrode holders with electrolytes containing chloride results in stable electrode potential. Suitable electrolytes include KCl, NaCl and CaCl2.