Research on magnetic nanoparticles of magnetite (MNPs) has intensified because it can be coated with different materials leading to diverse properties. In this work, MNPs and silica coated MNPs were synthesized by co-precipitation of Fe(III) and Fe(II) precursors, different proportions of tetraethylorthosilicate (TEOS), and scales showing high reproducibility and proximity of crystalline domains. Spectra of FT-IR exhibited the formation of Si–OH–Fe bonds. TEM images revealed that most of the MNPs were spherical with a fair distribution of encapsulated nanoparticles. Magnetization increased as the amount of silica coating increases. Silica coating did not modify the shape and structure of the MNPs cylindrical mesoporous open in the extremities. Adsorption of pyridine on the MNPs demonstrated the presence of hydrogen bonding, Lewis and Brønsted sites. For MNPs coated with silica, there was a neutralization of the Brønsted leading to weaker Lewis (coordinatively unsaturated iron) and hydrogen bonding sites (silanol groups).