Launched on 20 March 2002, U-31 was commissioned alongside her sister ship U-32 by German Minister of Defence Peter Struck in Eckernförde on 19 October 2005.

U-31 is propelled by one diesel engine and an electric motor driven by nine fuel cells, making the submarine virtually undetectable.

[citation needed] U-31 was built in two sections, the stern and propulsion by Nordseewerke, Emden and the bow at Howaldtswerke-Deutsche Werft, Kiel.

The fuel cells are virtually emission free, with the exception of distilled water, resulting in less noise, heat and exhaust fumes.

U-31 and U-32 were commissioned in a joint ceremony at Eckernförde on 19 October 2005 by Defence Minister Peter Struck, in the presence of the Inspector of the Navy Vice- Admiral Wolfgang E. Nolting.