The protonic conductivity of (1 -x)RbH2PO4-xSiO(2) composites prepared by mechanical milling has been investigated in the humid atmosphere. In comparison with pure RbH2PO4, the conductivity enhancement was observed and it was strongly dependent on the amount of SiO2 additives At low-temperature (LT) phase, the conductivity of composites increased with the addition of SiO2 till x=0 6 at which the maximum conductivity reached At high-temperature (HT) phase, it was approximately equal to that of pure RbH2PO4 and almost kept unchanged till x=0 5 Therefore, the jump in conductivity at similar to 280 degrees C (superprotonic phase transition temperature of RbH2PO4) tended to decrease as x increased and finally disappeared Furthermore, the conductivity of both LT and HT phases went down at large x values. The conductivity enhancement has been confirmed not to be influenced by absorbed water on the surface of SiO2 particles In fact, it is due to the formation of structurally disordered or amorphous Interface phase Also, we summarized the different theoretical models of the conductivity enhancement in composites (C) 2010 Elsevier Ltd All lights reserved