The new single ion conductors, poly(oligo-oxyethylene methacrylate-co-alkali metal acrylamidocaproic acid) ((CH2CCH3COO(CH2CH2O)(9)H)(x)-(CH2CHCONH(CH2)(5) COO(-)M(+))(1-x)), M(+)=Li+,Na+,K+, were synthesized and the effects of the cation and the temperature on ionic conductivity were investigated. The alkyl spacer in the alkali metal acrylamidocaproate was introduced to increase the flexibility of the side chain for the complex formation between the ionic groups and the oxygens in PEO unit. The room temperature(30 degrees C) conductivity of the K single ion conductor was found to be 5x10(-7) S/cm which is the highest value reported for the single ion conductors having carboxylate groups without any additives. The pseudo-activation energy in the VTF equation was not dependent on the type of the cation, which indicates that the ion hopping rate is higher than the string renewal rate in these single ion conductors.