The direct synthesis of hydrogen peroxide (H2O2) from molecular hydrogen and oxygen could represent a green and economically attractive alternative to the current indirect anthraquinone process used for the industrial production of hydrogen peroxide. This reaction has been investigated using palladium supported on the Cs-containing heteropolyacid Cs2.5H0.5PW12O40. In addition, the effect of adding copper as a potential activity promoter was investigated. These catalysts were also evaluated for the subsequent degradation of hydrogen peroxide. The catalytic activity of the 0.5wt%Pd/Cs2.5H0.5PW12O40 catalyst towards hydrogen peroxide synthesis was greater than that of both the mono-metallic Cu or bi-metallic Pd-Cu analogues with the incorporation of Cu to Pd resulting in a significant decrease in catalytic selectivity for the formation of hydrogen peroxide. Moreover, 0.5wt%Pd/Cs2.5H0.5PW12O40 also showed low activity towards the degradation of hydrogen peroxide. Hence the use of the Cs-containing heteropolyacid as a support for Pd gives higher rates of hydrogen peroxide formation when compared with different supported Pd catalysts prepared using supports used in previous studies.