In this study, an α-Keggin-type polyoxometalate H5PV2Mo10O40 was loaded into the adamantane cage (18 Å) of MOF-808(Ce) by an immersion method to obtain composites with different polyoxometalate loadings. The effects of the H5PV2Mo10O40 loading in the composite, the reaction time, and the quantity of the composite during the decontamination of the erosive agent surrogate, 2-chloroethyl ethyl sulfide (CEES) were investigated, and the optimized catalytic conditions for CEES were determined. The decontamination rate of 4 μL CEES reached 93.91% in 120 min using 40 mg of optimized composite, and the decontamination rate of 160 μL of the nerve agent surrogate, methyl paraoxon (DMNP) reached 100% in 25 min using 5 mg of the composite. Decontamination of CEES and DMNP by the composite followed first-order reaction kinetics. The half-life (t1/2) and kinetic rate constant (k) of these two reactions were 27.77 min and −0.02496 min−1 and 1.895 min and −0.36569 min−1, respectively. The composite exhibited good decontamination performance after four replicate experiments. The results showed that CEES was oxidized to CEESO, while DMNP was hydrolyzed to p-nitrophenol and dimethyl phosphonate in the presence of the composite, showing that the proposed composite is an effective bifunctional catalyst for the selective oxidation and hydrolysis of chemical warfare agent surrogates.