In the present work, peculiarities of beta --> alpha hydride transformation in subsurface layers of a beta-hydride of palladium in the temperature range 270-100degreesC were studied. The transformation processes were fixed with video camera in real time and then video movies were analyzed with a Pentium computer. It is shown that a decrease in internal hydrogen phase stresses and hydrogen concentrational ones with increase in temperature strongly influences both morphological peculiarities and the rate of transformation. So, at temperatures of 100-190degreesC the generation and growth of nuclei can be seen clearly. The features of transformation change with decrease in temperature: at 150degreesC, nuclei appear one another, the incubation period in subsurface layers consists of 8 s. At 190-170degreesC, nuclei appear simultaneously without any incubation period. At temperatures of 230-270degreesC, the transformation proceeds without any relief on the sample surface. The transformation in subsurface layers of a beta-PdHx, accelerates with temperature increasing from 100degreesC up to 150degreesC more than 700 times. (C) 2002 Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.