It has a single relatively large, leathery leaf and up to twenty large flowers that range in colour from pink to reddish but have a distinctive arrangement of lobes above the anther.Thelymitra epipactoides is a tuberous, perennial herb with a single fleshy, channelled, linear to lance-shaped, dark green leaf 150–250 mm (6–10 in) long and 15–20 mm (0.6–0.8 in) wide with a reddish base.

The flowers range in colour from pink to greenish, greyish or pale blue and to orange, reddish or bronze, often with a coppery sheen.

[2][3][4] Thelymitra epipactoides was first formally described in 1866 by Ferdinand von Mueller in Fragmenta phytographiae Australiae from a specimen collected near Port Phillip.

[5][6] The specific epithet (epipactoides) is derived from the name of the orchid genus Epipactis with the Latin suffix -oides meaning "likeness".

[7] The metallic sun orchid grows in grassland, heath and forest in southern Victoria, and in the Murraylands, Eyre Peninsula and south-east corner of South Australia.