The deNO (x) catalytic properties of a new class of open-framework structure materials, Li-6[Mn-3(H2O)(12)V18O42(XO4)] center dot 24H(2)O (X = V, S) (1), [Fe-3(H2O)(12) V18O42(XO4)] center dot 24H(2)O (X = V, S) (2), [Co-3(H2O)(12)V18O42(XO4)] center dot 24H(2)O (X = V, S) (3), and Li-6[Ni-3(II) (H2O)(12)V-16 (V2O42)-V-VI-O-V(SO4)] center dot 24H(2)O (4), have been studied. The crystal structures of these novel systems consist of three-dimensional arrays of vanadium oxide clusters {V18O42(XO4)} , as building block units, interlinked by {-O-M-O-} (M = Mn, 1; M = Fe, 2; M = Co, 3; M = Ni, 4) bridges. Their open-framework structures contain cavities, similar to those observed in conventional zeolites, which are occupied by exchangeable cations and/or readily removable water of hydration. The catalysts derived from these materials were tested for the selective catalytic reduction (SCR) of nitrogen oxides {NO (x) } into N-2 using a hydrocarbon, propylene, as the reducing agent. The catalysts were ineffective under lean burn conditions. However, the new catalysts, especially the one derived from the cobalt derivative (3), showed intriguing deNO(x) activity under rich conditions. They remove up to similar to 99% of the toxic NOx emissions in 1.5% O-2 with 100% selectivity to N-2. The active phase of the catalysts exhibit good stability, can be readily regenerated, and are selective to the desired product-N-2. The catalytic reactions occur at moderately low temperatures (400-500 degrees C). The catalysts were characterized by FT-IR, temperature programmed reactions (TPR and TPO), SEM, BET surface area measurements, elemental analysis, and X-ray diffraction (XRD). Additional advanced techniques were used to further characterize the catalyst phases that showed most promising deNO (x) activity and increased tolerance to oxygen.