Instead of Wikipedia how about some professional journal or magazine articles. Try this one: MRS Bulletin, Sep. 2002 - all about H-storage materials including Pd. Another good one: Hydrogen-storage materials for mobile applications, Louis Schlapbach & Andreas Züttel, NATURE , VOL 414, 15 NOVEMBER 2001.

Look at the Pd-H phase diagram (try google.scholar.com or Web of Science search engines) which will give you information regarding hydrogen absorption/desorption of H in Pd as a function of temperature and H pressure. In general, lower temperatures are needed to absorb H into Pd at modest to high H pressures. Different hydride phases of Pd-H exist. Usually, you desorb or remove H from the hydride by heating to higher temperatures (>100 C). Both volumetric and gravimetric storage capacity of Pd or other materials are important considerations; however, kinetics of absorption/desorption and temperature at which this occurs are also important factors. Cost is obviously very important too, so Pd is unlikely to be used as bulk hydrogen storage material for fuel cell applications.

I suspect this topic excites people in view of hydrogen storage as automotive fuel. In this connection, a very interesting way was proposed by Dr. Shelby from the USA. It consists in hydrogen loading into glass hollow microspheres (by using in engine hydrogen shell be outgassed from microballoons by action of laser beam). This way promises to be cheaper in comparison with metal techniques where noble materials are needed.