The present invention relates to a pelargonic acid formulation in the form of an oil-in-water emulsion and the use thereof for controlling undesired vegetation. The herbicidal pelargonic acid formulation according to the invention comprising:a) as component A, pelargonic acid or a mixture of aliphatic C6-C10-carboxylic acids with a pelargonic acid content of at least 80% by weight based on the total weight of the mixtureb) as component B, at least one organic solvent which under standard conditions has a water solubility of below 1 g/l and which has a boiling point of above 130° C. at standard pressurec) as component C, at least one surface-active substance which is selected among compounds of the formula Iin which n represents 0 or 1, R1 represents a linear or branched C6-C22-alkyl radical or a linear or branched C6-C22-alkenyl radical and R2 and R3 independently of one another represent hydrogen or a C1-C4-alkyl group d) as component D, at least one nonionic surfactant which is selected among substances which include at least one poly-C2-C4-oxyalkylene group e) as component E, at least one amino acid with an isoelectric point in the range of from 5 to 7, and f) water.
