The effects of the alkali doping on the reducibility and morphological properties together with distribution and crystallography of phases of a Ni/SiO2 catalyst have been investigated by N-2 adsorption measurements, diffuse reflectance TR Fourier transform spectroscopy (DRIFTS), CO adsorption, DRIFTS determinations, temperature-programmed reduction (TPR), X-ray diffraction line broadening (XRDLB), H-2 chemisorption, and TEM observations. Alkaline dopants produce an increase in the weakly adsorbed fraction of hydrogen and important changes in the adsorption modes of CO. Lithium and potassium modify the distribution of Ni across the support, inducing sintering phenomena, while sodium keeps nickel particle dispersion.