A number of M-Cu-ZSM-5 (M = La, Ni, La-Ni) samples were prepared via an aqueous solution ion-exchange method. The co-doping with Ni and La into a Cu-ZSM-5 catalyst enhanced the NO decomposition activity in a temperature range 350-550 degrees C. The characterization results indicate that doping with La effectively improved the dispersion of the Cu species forming more Cu2+ ions in the sample, while the effect of Ni is likely to facilitate the implantation of Cu2+ to form (Cu2+-O2--Cu2+)(2+) dimers. The synergistic effect of La and Ni contributes to the increased (Cu2+-O2--Cu2+)(2+) content in the co-doped sample, thus enhancing the NO decomposition activity.