The wood duck is a medium-sized perching duck, also known as the American Wood Duck. A typical adult is from 47 to 54 cm (19 to 21 in) in length with a wingspan of between 66 to 73 cm (26 to 29 in). This is about three-quarters of the length of an adult mallard. It shares its genus with the Asian Mandarin duck (Aix galericulata).

The adult male has distinctive multicoloured iridescent plumage and red eyes, with a distinctive white flare down the neck. The less-colourful female has a white eye ring and a whitish throat. Both adults have crested heads.

The male’s call is a rising whistle, jeeeeee; the females utter a drawn-out, rising squeal, do weep do weep, when flushed, and a sharp cr-r-ek, cr-e-ek for an alarm call.