Cassia siamea is a medium sized evergreen tree having a great many branches. The leaves are arranged in cascades and the flowers hang in bunches not unlike grapes. The petals are yellow and are from 5 cm to 7 cm in length.  The tree can be utilized to reforest denuded hills and mining sites, as host for sandalwood, for shade and hedges, as windbreaks, and it can be planted as an ornamental.

The dense, dark-coloured wood of S. siamea makes good fuel, although it produces some smoke when burning. The energy value of the wood is 22 400 kJ/kg, and the density is 600-800 kg/m³. The wood was formerly preferred for locomotive engines. Its charcoal is also of excellent quality.  The wood is hard to very hard, resistant to termites, strong, durable, difficult to work, with a tendency to pick up in planing and it takes a high polish. Sapwood is permeable to pressure impregnation.

The dark heartwood of S. siamea, which is often nicely figured, is used for joinery, cabinet making, inlaying, handles, sticks and other decorative uses. The wood has also been used for poles, posts, bridges, mine poles and beams.
All parts of the plant can be used for tanning.

The concentrations of tannin vary slightly from 17% in the leaves to 9% in the bark and 7% in the fruits.
In traditional medicine, the fruit is used to charm away intestinal worms and to prevent convulsions in children. The heartwood is said to be a laxative, and in Cambodia a decoction is used against scabies.

Cassia siamea functions as an excellent tranquilliser and has also been described as an anxiolytic (anti anxiety agent). Furthermore, it has some analgesic (pain killing) and diuretic (promoting the removal of excess fluid) properties. In contrast to its pharmaceutic counterparts, cassia siamea does not produce side effects or toxicity, has no lethal dose, and above all does not lead to dependency (addiction). Cassia siamea is also a first class psycho pharmaceutical.