High-melting-point alkylammonium tetrafluoroborates melt with water or toluene to form biphasic mixtures at much lower temperatures than their normal melting points, thus could serve as green reaction media for Suzuki and Heck couplings. Advantages of using the aqueous-ammonium biphasic catalytic system include: (1) working well with a ligandless palladium catalyst, (2) solving the solubility problem of organic substrates and (3) simplifying work-up procedures for both separation of products and recycling of reaction media. (C) 2003 Elsevier B.V. All rights reserved.