Permethrin is a photostable synthetic pyrethroid manufactured for insecticidal use. This invention discloses an improved process for the manufacture of permethrin without use of any solvent or catalyst, comprising reaction of 2,2-dimethyl-3-(2’,2’-dichlorovinyl)-cyclopropane-carboxylic acid chloride and 3-phenoxybenzyl alcohol, at 60-800C, with means for continuously expelling hydrochloric acid generating in the said reaction, from the reaction mass, into a HCI gas scrubber.
