Melicope molokaiensis are sprawling shrubs 2–4 meters tall or sometimes as small trees up to approximately 7 meters tall. The new growth is characterized by minutely yellowish-brown appressed puberulent branches that usually become glabrate. The leaves are simple and opposite, with broadly elliptic to suborbicular or ovate blades, sometimes appearing obovate–elliptic, measuring 3–12.5 cm in length and 2–8 cm in width. The apex of the leaves is rounded and occasionally emarginate, while the base ranges from subcordate to subtruncate or broadly cuneate. The leaf surfaces are mostly glabrate; young leaves are sparsely minutely puberulent, and the midrib on the lower surfaces is sometimes persistently short–hirtellous. The leaves are coriaceous and become brittle with age. The margins are somewhat revolute. Veins are pinnately arranged, with 6–9 pairs of primary lateral veins connected by a moderately arched vein located 2–6 mm from the margin, occasionally showing a few intervening reticulations. The petioles measure 5–28 mm in length, with some extending over 10 mm. Stipules are absent. The flowers are in axillary cymes containing 3–5(–9) flowers, extending to 3 cm long. These are sparsely minutely puberulent and slightly waxy scurfy. Peduncles are 5–20 mm long, and pedicels range from 2–8 mm long. Bracteoles are 1.5–2 mm long. The calyx consists of 4 sepals that are broadly ovate and about 2.5 mm long, both minutely puberulent and minutely ciliate. The corolla features four valvate, broadly deltate-ovate petals, each 4–5 mm long, approximately 2.7 mm wide, and glabrous. There are eight stamens arranged in 2 whorls. The ovary is superior, glabrous, 4-celled, and 4-lobed, with connate carpels but distinctly separate at the apex. Each cell contains two hemitropous ovules, with one ascending. The style is about 1.7 mm long and terminates in 4 short stigmatic branches. The fruits are capsules measuring 21–39 mm wide with carpels that are connate about ¼ of their length and dehisce along the upper suture. The seeds are 2.25–2.50 mm long, 1–2 per cell, glossy black when ripe, and crustaceous. The embryo is straight within a fleshy endosperm with a short radicle and compressed ovate cotyledons. It is found in mesic to wet forest habitats between 760-1270 meters, particularly between 850-1070 meters.