It has grey or grey-brown rough, shortly fibrous bark that is persistent on the trunk and larger branches.

Young plants and coppice regrowth have stems that are square in cross-section and leaves that are arranged in opposite pairs near the ends of the branches, then alternate, lance-shaped, 35–82 mm (1.4–3.2 in) long, 10–38 mm (0.4–1 in) wide and have a petiole.

The mature flower buds are green or yellow to reddish brown, oval, oblong or pear-shaped, 5–10 mm (0.20–0.39 in) long and 3–6 mm (0.1–0.2 in) wide with a rounded to conical operculum.

[3][4][5] Eucalyptus brachycalyx was first formally described by the botanist William Blakely and the description was published in his book Key Eucalypts.

[4][7] Gilja is found on sand dunes and limestone plains along the south coast in the Goldfields-Esperance region extending from the Fitzgerald River National Park in the west to the South Australian border.