The substitution of silica gel for gamma-Al2O3 to be used as a support for a nickel sulfide catalyst for stearic acid decarbonylation leads to a significant increase in the catalyst activity and a slight improvement of the heptadecene selectivity. Comparison with the gamma-Al2O3-supported catalyst has been made in terms of the kinetic model based on experimental data. An increase in the catalyst activity is attributed to a decrease in the strength of the active site-reactant adsorption complexes on the basis of the Sabatier-Balandin principle. Relationships between the features of the reaction mechanism, the acidity of the support, and the nanoparticle size of the active substance have been discussed.