Gel polymer electrolytes (GPEs) are prepared with methyl methacrylate (MMA)-styrene (ST) copolymers and LiPF6 or LiBF4 in ethylene carbonate/dimethyl carbonate. Depending on the molar composition of the copolymer, these gel polymer electrolytes exhibit a different range of mechanical and electrical properties. On the aspect of ionic conductivity and mechanical property, the copolymer comprising about 33 mol% MMA is found to be most desirable. Lithium-ion polymer cells employing GPE containing different electrolyte solution are assembled and their cycling performances are evaluated.