All-solid-state proton batteries are promising energy storage systems, in which the solid-state proton electrolyte plays an important role. However, achieving fast proton conduction over a wide temperature range is challenging. Here, we report zirconium hydrogen phosphate (ZHP) as a solid-state proton electrolyte. It shows ultra-high proton conductivity from -40 to 120 °C (0.15 to 66.76 mS·cm^-1), a wide stability window (~5.5 V), and excellent long-term stability. Batteries using ZHP as electrolyte exhibit stable operation over a wide temperature range (160 °C), and retain 92% capacity after 12,000 cycles at room temperature. After 1,000 cycles, the batteries retain 100% capacity at -30 °C and 84.5% at 40 °C. This work provides new insights into the design and application of all-solid-state proton batteries capable of operating over a wide temperature range.