A pure-inorganic framework based on {P4MoV4MoVI2} clusters with rich phosphate groups has been synthesized. It underwent a single crystal to single crystal conversion in air to form a new framework with changes both in the metal valent state and coordination environment. The new framework exhibits an ultra-high proton conductivity of 1.33 × 10-2 S cm-1 at 95 °C and 98% relative humidity and excellent stability.