The deposition-precipitation (DP) method was used for the preparation of Ni/SiMCM-41 and Ni/AlMCM-41 catalysts with different DP times (1-4 h), and the catalysts were characterized by BET, XRD, TPR, FTIR spectroscopy, and TEM. On both types of catalysts, the Ni(II) phases formed are a mixture of 1:1 nickel phyllosilicate and Ni(OH)(2). The quantity of each phase at the end of the deposition process determines the final Ni particle size; i.e., greater amounts of Ni(OH)(2) lead to larger Ni particles. In addition, it was found that the presence of aluminum in the framework of MCM-41 delays the formation of the nickel hydrosilicate phase. As a result of the consumption of the siliceous pore walls during DP, the long-range order of the MCM-41 hexagonal pore structure is gradually lost. Catalytic activity in the hydrogenation of naphthalene was higher for Ni/SiMCM-41 catalysts and was a linear function of the exposed area of Ni particles.