Potential step chronoamperometry and electrochemical impedance spectroscopy measurements were performed on single metal hydride (MH) particles. For the alpha phase, the bulk diffusion coefficient and the absorption/adsorption rate parameters were determined. Materials produced by atomization, melt spinning, and conventional casting were investigated. The melt spun and conventional cast materials were identical and the atomized material similar in composition. The particles from the cast and the melt spun material were shaped like parallelepipeds. A corresponding equation for this geometry, for diffusion coupled to an absorption/adsorption reaction was developed. It was found that materials produced by melt spinning exhibited lower bulk diffusion (1.7 x 10(-14) m(2) s(-1)) and absorption/adsorption reaction rate (1.0 x 10(-8) ms(-1)), compared to materials produced by conventional casting (1.1 x 10(-13) m(2) s(-1) and 5.5 x 10(-8) ms(-1), respectively). In addition, the influence of particle active surface and relative diffusion length were discussed. It was concluded that there are uncertainties connected to these properties, which may explain the large distribution in the kinetic parameters measured on MH particles. (C) 2003 The Electrochemical Society.