Hydrogen gas absorption Palladium and reaction in cold water

I recently purchased a one ounce palladium round shape as a coin, knowing that palladium absorbs hydrogen gas and after absorption Palladium do some different action in a glass of cold water. I decided to see if this was true. So I then went and set up electrolysis apparatus where the hydrogen gas would be directed through some tubing right onto the palladium one ounce coin I have. I did this little 'electrolysis' for quite a while to ensure that a good deal of hydrogen gas would get absorbed onto the palladium. After about five hours of continuous electrolysis, I went and keep it in a glass of cold water and wait for result, yes it is very true that after thirty minute the coin coming up very slowly and then it remaining floating in the glass of water. The palladium coin was heavier! but it did the amazing action. Can some one give a scientific explain or solution why did it ??? please take a experiment and help me to know about this amazing behavior by the absorption palladium. had indeed absorbed a great deal of hydrogen gas.