íXmOöC³ºjIP AlH 2 P 3 O 10 E nH 2 O mÀè«gÓéÄï`±Á« cDÀEìcE{R åw ¶YZp¤C1538505 sÚaeîê 461Stability and proton conductivity of AlH 2 P 3 O 10 EnH 2 O (n23) were investigated in the temperature range from 75 C to 150 C under various water vapor pressures. The hydrolysis from AlH 2 P 3 O 10 EnH 2 O to Al(H 2 PO 4 ) 3 started at 100 C under a relative humidity (RH) of 60÷, and further hydrolysis to AlPO 4 took place with increasing temperature and humidity. At 75 C, the original phase was maintained under saturated water vapor pressure. Conductivity measurements at 75 C (0÷RH98÷) and 100 C (0÷RH60÷) in dicated an abrupt increase in conductivity with increasing water content n in the range of n1.0 to 2.0 at both temperatures. The proton conductivity achieved a value s5.0~10 |3 SEcm |1 at 75 C and 98÷ RH. It is assumed that the proton conductivity in the crystal became larger by formation of continuous hydrogen bonding in AlH 2 P 3 O 10 EnH 2 O.