you can do it by measuring the amount of Hydrogen gas evolved ( volumetrically ) using a burette by the displacement of water

Thank you very much for your valuable advice sir Muralidharan...But, since I am working at a very low concentration(mmol) the expected evolved amount is also must be too low to collect it by displacement method..Is there any other way to prove it that this is actually evolved..and also in that much(?) amount..!!

You can measure even very low concentrations using peak areas of standard and your sample.

first plot the standard plot for the different concentration of hydrogen using GC with appropriate detector which can be able to measure your hydrogen accurately. then you can inject  your sample to check the hydrogen production....