Shell-core type TiP2O7-based electrolytes were synthesized by a low-temperature sol-gel method, and their conductivities were investigated by ac-impedance spectroscopy. The samples heat-treated at 500°C showed higher proton conductivities of 3.8 × 10-2 - 1 × 10-2 Scm-1 at intermediate temperatures (100 - 300°C). The conductivity decreased by reheat-treatments at 600°C and 700°C due to a decrease in the amount of the conductive amorphous shells. However, the mechanical strength of the sample pellet significantly increased by the reheat-treatment. The sample reheat-treated at 600°C kept high conductivities of 8.8 × 10-3 - 1 × 10-3 Scm-1 in a range of 100°C - 300°C.