To understand the mechanism of ionic diffusion through membranes the membrane resistance, capacitance and impedance of parchment supported Iron phosphate, cupric phosphate and complex ironcupric phosphate membranes have been analyzed. The electrical resistance (Rx), and capacitance(Cx) developed across these membranes have been measured at different electrolyte concentrations and oscillator frequencies.

The obtained  values of membrane resistance(Rm), membrane capacitance(Cm), impedance(Z) were found to dependent on the concentration of the electrolyte and on the applied oscillator frequency at isothermal temperature (25±0.1°C). The electrical double-layer at the membrane-electrolyte interface was influenced and controlled by the transport of ions. An increase in concentration of electrolyte solution causes the counter ions in the form of double-layer inside the membranes makes membrane more conductive. Different model-equivalent electrical circuits against to membranes have been analyzed using the experimental data. There is a deviation from theoretical predictions in Membrane resistance, capacitance and impedance due to roughness and non homogeneity of the membranes used in present investigation.