A new NH3-reduction method was developed for the preparation of Ni-Ce0.12Zr0.88O2 catalysts with different Ni loadings (5, 10, and 15 wt %). The reduction of the catalysts was performed in a tube furnace with NH3 or H-2. The catalysts were characterized using Brunauer-Emmett-Teller, inductively coupled plasma-optical emission spectroscopy, X-ray diffraction, transmission electron microscopy-high-resolution transmission electron microscopy/energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, and CO pulse chemisorption techniques. The catalytic activity toward the CO and CO2 methanation reaction was investigated. The results showed that the NH3-reduction method lead to a higher active metal reducibility, smaller Ni-0 crystallite size, and higher metal dispersion compared to the H-2-reduction method with 100% CO and 97% CO2 conversions and >= 98% CH4 selectivity at 250 degrees C.