Method for manufacturing optically transparent gel-polymer electrolytes includes reaction of copolymerization of melamine and formaldehyde or melamine and glyoxal with one or several polyols and/or with one or several monosaccharides, oligosaccharides or polysaccharides and adding of a concentrated acid to form an optically transparent gel-polymer. The electrolyte according to the invention can be used in electrochromic devices and other optical-electrochemical devices as well as in devices for storing electrical energy (such as batteries, supercapacitors and hybrid power storage devices), thus replacing conventional water-based electrolytes.