For an effective and safe usage of phenoxyalkanoic acid herbicides a wide knowledge of their physical and chemical properties is essential. An understanding of their mode of action, absorption, and translocation within plant and animal tissues is required. The molecular structure of the phenoxyalkanoic acid herbicides consists of a halogen, primarily chlorine, and occasionally an alkyl substituted aromatic ring bonded to a carboxylic moiety through an ether linkage. Although the major use of phenoxyalkanoic herbicides is associated with weed control in dry land vegetation, some of them are also used to kill aquatic weeds in lakes and ponds. The phenoxyalkanoic acids have limited toxicity to mammals, fish, shellfish, insects, and aquatic microorganisms. The phenoxyalkanoic acid herbicides are marketed either as their water soluble salts of alkali metals and aliphatic amines or in the ester form as emulsifiable concentrates and solutions in oils.