A dry-state bioelectrode having a self-sealing receptacle for receiving electrolyte and/or medicament fluid contents. The receptacle is attached at its opening to a sheet-like flexible base member having an opening in common with the receptacle opening, the bottom of the base member being adapted for fixation at a skin surface. A portion of the skin surface is exposed to the fluid contents of the receptacle through the common opening. An injection site communicates through the wall of the receptacle and provides controlled access for filling. Upon completion of filling, the receptacle self seals, retaining the fluid contents therein for application of iontophoresis treatment or other procedures requiring use of a potential gradient. An electrode plate is supported at an interior surface of the receptacle for supplying the desired electric potential.