2,4,5-三氯苯氧乙酸，也称2,4,5-涕或2,4,5-T，可用作植物的生长调节剂、除草剂。纯品为白色无臭晶体，难溶于水，对人体有一定危害。根据不同植物施用适当计量，可以防止植物落花落果，但用量不当会使植物受到严重伤害。 2,4,5-三氯苯氧乙酸具有一定的毒性，对老鼠的LD₅₀是389mg/kg ，而大鼠是500 mg/kg。

美军在越战时于越南所喷洒的橙剂之中，即含有2,4,5-T。

2,4,5-Trichlorophenoxyacetic acid (also known as 2,4,5-T), a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants. It was developed in the late 1940s and was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns. Agent Orange, a defoliant used by the British in the Malayan Emergency and the U.S. in the Vietnam War (Vietnam Conflict), was equal parts 2,4,5-T and 2,4-D (2,4-dichlorophenoxyacetic acid). 2,4,5-T itself is toxic with a NOAEL of 3 mg/kg/day and a LOAEL of 10 mg/kg/day. Additionally, the manufacturing process for 2,4,5-T contaminates this chemical with trace amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD is a carcinogenic persistent organic pollutant with long-term effects on the environment. With proper temperature control during production of 2,4,5-T, TCDD levels can be held to about .005 ppm. Before the TCDD risk was well-understood, early production facilities lacked proper temperature controls and individual batches tested later were found to have as much as 60 ppm of TCDD.