Boroxine ring containing additives, Bx(n)=B3O3[O(CH2CH2O) n CH3]3, were found to be compatible with a wide variety of polymer hosts. Polymer electrolytes exhibiting room temperature conductivities of up to 10−5 S cm−1 were obtained by incorporation of Bx(n) and LiCF3SO3 into poly(methyl methacrylate) and propylene oxide–ethylene oxide co-polymers. Polymers composed of inter-connecting networks of boroxine rings were also investigated as suitable hosts for the boroxine additives B3O3[O(CH2CH2O) n CH3]3. Poly(methyl methacrylate) systems exhibited an electrochemical stability window in the region of 4.9 V, while transference number measurements indicated high Li+ ion conductivity.