Development of new materials that can be applied as solid electrolytes has led to the creation of modern systems of energy generation and storage. Among these materials, polymer electrolytes (PEs), generally elastomeric materials containing ions, represent a promising alternative for the substitution of liquid electrolytes and inorganic crystals used in batteries, sensors and electrochromic devices. Among different poly(ethylene oxide) based PEs, natural polymer based systems are also proposed. These ionic conducting materials can be obtained from polysaccharides, such as cellulose derivatives, i.e., hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC) or carboxymethylcellulose (CMC), starch, starch derivatives and chitosan, proteins like gelatin or more recently DNA. These systems can be modified by grafting, crosslinking or plasticization processes. After salt or acid addition, the samples in the transparent film form exhibit ionic conductivity values, which reach 10-4 S/cm at room temperature and can be applied to electrochromic devices. The paper review the main results of preparation and ionic conductivity characterization of polymer electrolytes based on agar, DNA and gelatin with emphasis on electrochromic devices application.