Solution casting technique has been used to prepared chitosan-based polymer electrolyte films. The polymer electrolyte (PE) film containing 55 wt.% of biopolymer chitosan, 45 wt.% of NH4I salt and 80 wt.% of 1-butyl-3-methylimidazolium iodide (BMII) displayed the highest room temperature ionic conductivity of 3.02 x 10(-)(4) S cm(-1). The interaction between components in the biopolymer electrolyte has been optically investigated. The configuration of indium tin-oxide (ITO)/TiO2/Ru-complex (N3) dye/biopolymer electrolyte/Pt/ITO dye-sensitized solar cells (DSSCs) were fabricated. DSSC with chitosan-based PE consist of 80 wt.% BMII exhibited the highest efficiency of 1.2%.