The effects of hydrogen (protium) or deuterium absorption/desorption cycling on the strength and hardness of well-annealed palladium have been evaluated in this study. The results indicate that absorption followed by complete desorption of hydrogen or deuterium increases the strength and hardness characteristics of the palladium matrix while decreasing the metal's ductility. Increasing the amount of hydrogen or deuterium during absorption leads to more pronounced effects on the strength, hardness, and ductility of palladium. The effects of hydrogen absorption/desorption are more pronounced than those of deuterium absorption/desorption. The observed results have been explained in terms of the generation of dislocations during hydrogen or deuterium cycling.