The direct synthesis of hydrogen peroxide from molecular hydrogen and oxygen represents an attractive alternative to the anthraquinone process in terms of atom efficiency. Supported Au-Pd catalysts have been shown to be extremely effective in the direct synthesis process especially when supported on acidic supports. Using acidic supports aids the stabilisation of hydrogen peroxide and can also decrease the subsequent hydrogenation and decomposition reactions. We report the preparation and testing of Au-Pd catalysts prepared by ion exchange and impregnation methods with insoluble heteropolyacids as the support. The heteropolyacids contain a range of counter ions including Cs+, Rb+, K+ and Ag+. The catalysts containing Cs and Rb prepared by ion exchange were shown to be extremely active for H2O2 synthesis using reaction conditions that are not particularly conducive to H2O2 synthesis but are reaction conditions that are dictated by potential applications, such as water as a solvent and ambient temperature. (C) 2014 Elsevier B.V. All rights reserved.