Glycine decorated heteropolymolybdates, K₂Na[AsMo₆O₂₁(O₂CCH₂NH₃)₃]·6H₂O 1 and K₂Na₂[γ-Mo₈O₂₆(O₂CCH₂NH₃)₂]·6H₂O 2, have been synthesized and evaluated for in vitro anti-proliferative effects. The identity and high purity of compounds 1 and 2 were confirmed by elemental analysis, FT-IR spectrum, UV–vis spectrum, and X-ray diffraction. Crystal data for 2: triclinic, P-1, a=9.792(2)Å, b=10.077(2)Å, c=10.351(2)Å, α=83.865(4)°, β=71.110(4)°, γ=62.284(3)°, V=854.3(3)ų, Z=1, R(final)=0.0486. The inhibitory effects of 1 and 2 on human non-small cell lung cancer cell line A549 were investigated by MTT assay, nuclear staining, and the flow cytometry. It indicated that compound 1 inhibited the proliferation of A549 cells in a dose-dependent and time-dependent manner, which is more effective than the positive control, 5-fluorouracil (5-FU) (P<0.05). The staining and flow cytometry results showed that compound 1 induced the apoptosis and necrosis of A549 cells and inhibit cell proliferation, which is associated with S-phase arrest. Compound 2 showed a modest activity in a dose-dependent manner. In addition, the interaction between compound 1 and bovine serum albumin (BSA) was evaluated by spectroscopic methods. The results showed that the compound 1 effectively quenched the intrinsic fluorescence of BSA via static quenching and changed the conformation of BSA.