Solution polymerization of trioxane (TO) with l,3-dioxolane {DO) gave copolymers of various comonomer compositions. TO was also copolymerized with ethyl glycidate (EG) and terpolymerized with DO and EG to polymers of low EG content. The copolymers were acetate endcapped or base treated to give stable co- and terpolymers. The treatment of EG containing polyoxymethylene (POM) copolymers with sodium hydroxide in methanol at elevated temperatures gave POM ionomers. The polymers were characterized by their infrared and PMR spec­tra for their general structure and co-and terpolymer composition. POM co­polymers with only EG as comonomer showed low base stability but those which contained ethylene oxide (EO), e.ither alone or in combination with EG, gave polymers of high base stability.