A process for producing a benzoxazine containing free aliphatic hydroxyl groups and monoester comprising the steps of: a) a reaction of a phenolic acid derivative with a monofunctional oligomer or molecule at a temperature of from 80 C. to 200 C., during 12 h-48 h, in a presence of a Bronsted type acid catalyst, resulting in a monophenol terminated oligomer or molecule and b) reaction of the monophenol terminated oligomer or molecule of step a) with a mixture of an amino-alcohol, a primary amine derivative and paraformaldehyde at a temperature range of from 80 C. to 100 C., from 1 h to 48 h, under stirring.

There is provided a composition for gel electrolyte that can impart excellent power characteristics and a high capacity retention ratio to an electrochemical capacitor. The composition for gel electrolyte comprises an electrolyte salt and a polyether copolymer having an ethylene oxide unit, wherein the composition for gel electrolyte has a water content of 50 ppm or less.