In a combined p-c and R/Ro-c study of Pd-5 and 9.9 at.% Ag-D systems by a gas phase method, a remarkable pressure and resistance hysteresis are observed between 298-323 K. Pressure hysteresis are gradually decreased with increasing the silver content. R/Ro value increases with increasing D/M content up to amax compositions. In the (α+β) two-phase region, R/Ro shows only a small increase. From β min , R/Ro increases abruptly with increasing D/M content. On desorbtion, R/Ro value decreases with decreasing D/M contents down to bmin and then remains almost constant in the (α+β) two-phase region. From α max(des), R/Ro sharply decreases to a minimum value. Finally, a large resistance hysteresis is observed in the (α+β) two-phase region. Such R/Ro-c hysteresis indicates that the creation of lattice strain deformations accompanied of dislocations for the β deuteride formation are not fully annihilated during the decomposition of β deuteride. The hysteresis is decreased with increasing temperature and silver content. For the Pd-5 at.% Ag-D system, no resistance hysteresis is observed between 348-398 K. In this case, R/Ro value is increased abruptly up to amax composition. (D/M)α max is appeared after a long holding. In the (α+β) region, R/Ro remains almost constant but decreases with increasing temperature. In this region, the dislocation densities for the a tb transformations behave as equal in quantity and R/Ro is insensitive to small change in dislocations. The sharp increment of R/Ro values up to (D/M)α max seems to be related to the Gorsky effect. The absence of resistance hysteresis indicates that the plastic deformations created due to the b deuteride formation are fully annihilated during its decomposition. Presently observed p-c and (R/Ro)-c behaviours are analogous to that found previously for Pd-H(D) and Pd-5 and 9.9 at.% Ag-H systems. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.