An electrolyte composition and catalyst ink, a solid electrolyte membrane formed by printing the electrolyte composition and catalyst ink, and a secondary battery including the solid electrolyte membrane. An electrolyte composition includes a solvent; a lithium salt dissolved in the solvent; and a cycloolefin-based monomer dissolved or dispersed in the solvent and a catalyst ink includes a catalyst that promotes the ring-opening and polymerization reactions of the cycloolefin monomers of the electrolyte composition.