background: 2, 4-dichlorophenoxy acetic acid (2, 4-d) is well known as inexpensive herbicides but it can give rise to undesirable pollution. the objective of this investigation was to describe a photo-chemical system for degradation of 2, 4-d. methods: a designed photolytic cell system was used in this study with a 150w or 400w uv lamp. a set of experiments was carried out at ph 1.5, 2.5, 3.5 a...