Abstract The epoxidation of alkenes with hydrogen peroxide or molecular oxygen, in the presence of aldehyde catalyzed by heteropolyoxometalate (HPOM) salts and layered double hydroxides (LDHs) containing HPOM anions as pillars, has been investigated. In the case of oxidation with hydrogen peroxide, a lacunary Keggin-ion, SiW 11 O 39 8− , was more active than SiW 12 O 40 4− . For this reaction system using hydrogen peroxide, intercalated SiW 11 O 39 8− showed higher stability in structure and activity than free K 8 SiW 11 O 39 . For the oxidation using molecular oxygen and aldehyde, SiW 12 O 40 4− showed higher activity than SiW 11 O 39 8− . It was confirmed that SiW 12 O 40 4− was intercalated between the brucite-type layers of the LDHs without change in structure. Ni-containing LDHs without any interstitial polyoxometalate showed high activity for the oxidation of cyclohexene with the combination of O 2 and aldehyde.