Melicope mucronulata is a small tree growing up to 4 meters tall, with new growth characterized by dense puberulence. The leaves are simple and opposite, featuring ovate to elliptic-ovate blades measuring 8–16 cm long and 3.5–6.5 cm wide. The upper surfaces of the leaves are glabrous, while the lower surfaces start densely puberulent in youth before becoming sparsely minutely puberulent or glabrate as they mature. The leaves are thin but coriaceous, with entire margins. The primary lateral veins, typically 6–8(–10) pairs, are connected by an arched vein 3–10 mm from the margin. This arrangement supports a pinnate venation pattern where the lateral veins are linked by an arched submarginal vein, with higher-order venation forming a reticulate pattern. The petioles measure 20–35 mm long, and the species lacks stipules. The flowers appear in groups of about 3–9 within axillary cymes and are puberulent throughout. These cymes feature 6–15 mm peduncles and 3–8 mm long pedicels. It features a calyx with four sepals and a corolla with four petals. There are eight stamens, and the superior ovary is 4-celled and lobed with carpels that are connate yet distinct at the apex. Each cell hosts two hemitropous ovules, one ascending; the style culminates in 4 short stigmatic branches. The fruit spans 24–28 mm wide and comprises 12–14 mm long follicles. The exocarp is thin and glabrous, and the carpels dehisce along the upper suture. Seeds are typically 1–2 per follicle, about 4.5-5.5 mm long, glossy black when ripe, crustaceous, and ovoid, occasionally angled from compression. The seeds contain an embryo embedded in the fleshy endosperm, with a short radicle and compressed, ovate cotyledons. The putamen is brown and warty. It inhabits mesic forests and dry shrublands at an elevation of 870 meters.