Old-fashioned romance techniques of a nice meal and a bunch of flowers have proven successful for NSW scientists playing cupid to a critically endangered species of mouse.

Numbers of the smoky mouse have dropped to critically low levels in the state's wild due to their "gentle and naive" natures, which make them highly vulnerable to predators.

Critically endangered smoky mice. Credit:AAP

The only two sites in NSW where the species can be found is the Nullica area on the South Coast and Kosciuszko National Park, the NSW government's Office of Environment & Heritage says.

Scientists have been working to increase the species' population numbers at a captive breeding facility outside Queanbeyan since July last year - and met with success after trying their hand at some old-school techniques.