Eighteen novel bis-ammonium herbicidal ionic liqs. were synthesized by partial or total bromide anion exchange in RMe2N+(CH2)(n)N+Me2R center dot 2Br(-) (where n = 4, 5 or 12 and R = Bu, C10H21, C14H29, C16H33, PhCH2 or i-Pr) to 4-chloro-2-methylphenoxyacetate and optionally to 3,6-dichloro-2-methoxybenzoate anions and studied for soly. in common solvents and herbicidal activity against cornflower (Centaurea cyanus L.), white mustard (Sinapis alba L.) and oil seed rape (Brassica napus L.). The herbicidal activity of the salts was comparable to a corn. herbicide (K or Na 4-chloro-2- methylphenoxyacetate).