A poly(methylene oxalate) polymer [poly(oxy(1,2-dioxo-1,2-ethanediyl)oxymethylene)], a bis(tetrabutylammonium)oxalate salt, methods of synthesis thereof and methods of use. Poly(methylene oxalate) is insoluble in all common organic solvents, does not melt and is resistant to fire. Applications are as a light-weight material for use at high temperatures, e.g. as a structural material in aircraft and space vehicles, as a binder for brake systems, and as an insulator for microelectronic components.