The mass‐transfer phenomenon between an aqueous‐organic phase and an electrode producing sulfur from sulfide ions in a parallel plate reactor is studied. A kinetic model of the electrochemical conversion and extraction process is developed and tested. Under steady‐state conditions, the electrochemical reaction rate at limiting operation, defined asK‘mA(1 –θ)CR/α,is equal to the extraction rate, defined asK‘dA θ(Csats/β‐ Cs/β) for this extractive electrochemical system. Experimental parameters include volume fraction (Xd) and fluid velocity (Re‘). The mass transfer coefficients,K‘mandK‘d,were obtained asK‘m=7.044 × 100–5Re‘?(1.073 + 0.575Xd– X2d) andK‘d= 5.15 × 10–4Re‘?Xdwith a Reynolds number between 18∼54 and volume fraction under 70% for this two‐phase solution.