An environmentally benign green protocol is introduced for the synthesis of simple derivatives of glycolurils through condensation of vicinal diketones, as well as glyoxal, with urea and methylurea by the mediation of a catalytic amount of simple acidic and anionic heteropolyoxometalates. H3PW12O40 and H4SiMo3W9O40 (Keggin types), 14 5 30 110 H NaPW O (Preyssler type), and K6P2Mo18O62 (Wells-Dawson type) revealed the best catalytic activity in the reaction of urea with 2,3-butanedione and led to the corresponding glycoluril quantitatively after 5.5 h.