The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis (CGDE) in a water electrolysis. Critical current density (CCD) and breakdown voltage were measured together with

in situ

observation of hydrogen bubble behavior

whose influence has not been focused on. For a fixed current during normal electrolysis

hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity. Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles. The CCD increased about 104% within given range of conductivity (11.50-127.48 mS·cm

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1

) due to impaired bubble coalescence

which delays hydrogen film formation on the cathode. Meanwhile

decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%. It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors

whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.