A method based on impedance spectroscopy has been utilized to obtain values of transport parameters such as number density, mobility and diffusion coefficient of mobile ions of solid polymer electrolytes (SPEs). SPE membranes consisting of chitosan and various amounts of oxalic acid (C2O4H2) from 10 to 50 wt% have been prepared by the solution casting method. The Nyquist plots of all electrolytes have been fitted using the impedance equations based on equivalent circuits, and the parameters involved have been evaluated by trial and error. Number density, mobility and diffusion coefficient of mobile ions were calculated based on the parameters obtained. The values obtained from the proposed electrical impedance spectroscopy method are in reasonable agreement with those calculated using the percentage of mobile ions obtained from Fourier transform infrared (FTIR) measurements. The results were further compared with the results obtained using broadband dielectric response or Bandara-Mellander approach. The findings were confirmed by repeating the measurements and calculations on a glycerol-chitosan-oxalic acid-based electrolyte.