This study reports an improvement of the stability of steam reforming catalysts at relatively low temperatures, such as for pre-reforming, and reforming of biomass derived compounds, by enhanced stabilization of Ni nanoparticles through spatial confinement in a mixed oxides matrix. We revealed a simple approach of three dimensional engineering of Ni particles by means of self-assembly of Ni atoms inside the nanoribbon of hydrotalcite-derived mixed oxides. Taking advantage of Transmission Electron Microscopy (TEM), together with electron tomography, the three dimensional (3D) structure of the catalyst was investigated at a nanometer scale, including the Ni particle size, shape, location and spatial distribution, as well as pore size and morphology of the mixed oxides. Porous nano-ribbons were formed by high temperature treatment, adopting the layer structure of the hydrotalcite-like materials. Ni particles formed by selective reduction of mixed oxides embedded in the nano-ribbons with connected pore channels, allowing good access for the reactants. These spatially confined and well distributed Ni particles increased catalyst stability significantly compared to the Ni particles supported on the support surfaces in a commercial catalyst during the steam methane reforming. © 2012 The Royal Society of Chemistry.