In this work, a plasticised carboxymethyl cellulose (CMC) solid biopolymer electrolytes (PSBEs) system was prepared via solution casting technique with ammonium acetate (NH4 CH3 COO), ethylene glycol (EG) as doping salt and plasticiser respectively. Upon addition of 35 wt.% of EG (PSBE 4), the ionic conductivity obtained is 1.81 × 10-5 Scm-1 which represents the optimum value for the system. The PSBE also tested at elevated temperatures and fitted to an Arrhenius equation. Fourier Transform Infrared Spectroscopy (FTIR) analysis found no significant changes to the molecular structure of CMC with addition of EG. Jonscher’s power law indicates that quantum tunnelling is the well-matched model to describe ionic conduction for PSBE 4 and it appears that it is also highly ionic with good transference number obtain from dc polarisation analysis technique.