TPR, XRD, TEM, and IR techniques were used for studying reduction of nickel-silica systems over the whole concentration range (nickel content was varied within the range 16 to 95%). The systems were prepared by the heterophase sol-gel method. It was established that the reduction temperature increased as the silica content increased from 0 to 34% in the system, the average size of nickel crystallites being decreased from 44 to 4.5 nm. At the further increasing the silica content (to 84%): the reduction temperature decreased while the nickel crystallites grew in size to 15 nm. Testing of the prepared systems in benzene hydrogenation showed that the surface of nickel particles was accessible to the reactants.