In this present work, the investigation of solid biopolymer electrolytes (SBEs)-based alginate-doped NH4Br was carried out and prepared via casting technique. The SBEs system was characterized using Fourier transform infrared, thermal gravimetric analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscope, and electrical impedance spectroscopy. Based on IR-analysis, it was shown that the complexation between alginate and NH4Br has occurred based on the changes of peak at COO- group of alginate. The interaction led to the improvement in amorphous phase and thermal stability of SBEs system when NH4Br was added. The ionic conductivity of SBEs system was found to achieve maximum value at 4.41 x 10(-5) S/cm when 20 wt. % of NH4Br was added and the value was comparable with other types of polymer electrolytes system. The temperature-dependence ionic conductivity of entire SBEs system obeys Arrhenius behavior where the R-2 1 and present system are thermally assisted. From IR-deconvolution approach, it can be found that the ionic conductivity of alginate-NH4Br SBEs system was governed by ions mobility, mu and diffusion coefficient, D. All these findings imply that present alginate-based SBEs system is potential to be applied in electrochemical devices, i.e., proton battery, supercapacitor and fuel cell.