In this study, the evolution of the stress states in RENi5 particles during hydrogen charging and discharging cycles were investigated using coupled diffusion-deformation finite-element method analyses. The results indicate that large tensile stresses, of the order of 20-30% of the modulus of elasticity, develop in the particles even in the absence of both internal and external crack-like defects. The internal and external cracks behave differently from each other during hydrogen charging and discharging cycles. Therefore, the fracture resistance of the particles containing external cracks will be different from the particles having internal cracks. The disc-shaped particles, in addition to having faster charging-discharging cycles, may offer better resistance to fracture than the spherical particles.