A process to obtain functionalized magnetic ferrites nanoparticles comprising the following steps: (a) initially a chemical synthesis is performed in a reactor, at a temperature ranging from 60 to 90°C, under stirring, fed with precursors salts such as nitrates, sulfates or chlorides, chemical solvents, in which bases or acids are added to pH adjustment, yielding as product a magnetic gel; (b) the magnetic gel from step (a) is submitted to a surface treatment in a second reactor through the addition of acids and bases in order to obtain the magnetic gel with the surface prepared for functionalization; (c) the magnetic gel obtained from step (b) is submitted to a primary washing by decanting with deionized water, removing the excess salts; (d) functionalization of the magnetic gel obtained in (c) through coprecipitation, adding polar and nonpolar functionalizing agents in order to form a magnetic particle with desired hydrophilic or hydrophobic surface characteristics, in which bases and acids are added for pH adjustment, where the yielded mixture is maintained under mechanical stirring and heating during the period from 1 to 4 hours; (e) the magnetic particles obtained in step (d) are submitted to a secondary washing by decanting, dialysis or filtration, with addition of deionized water and organic solvents, removing the excess functionalizing agents; (f) the material obtained in step (e) is submitted to a controlled drying step, through hypercritical drying, freeze-drying or spray drying, in which the functionalized magnetic gel is transformed in a functionalized nanoparticulate powder; (g) the functionalized nanoparticulate powder obtained from step (f) is packed, preferably in an airtight plastic, in order to be commercialized as powder, or dispersed in a solvent and bottled to be commercialized as ferrofluid. (a) initially a chemical synthesis is performed in a reactor, at a temperature ranging from 60 to 90°C, under stirring, fed with precursors salts such as nitrates, sulfates or chlorides, chemical solvents, in which bases or acids are added to pH adjustment, yielding as product a magnetic gel; (b) the magnetic gel from step (a) is submitted to a surface treatment in a second reactor through the addition of acids and bases in order to obtain the magnetic gel with the surface prepared for functionalization; (c) the magnetic gel obtained from step (b) is submitted to a primary washing by decanting with deionized water, removing the excess salts; (d) functionalization of the magnetic gel obtained in (c) through coprecipitation, adding polar and nonpolar functionalizing agents in order to form a magnetic particle with desired hydrophilic or hydrophobic surface characteristics, in which bases and acids are added for pH adjustment, where the yielded mixture is maintained under mechanical stirring and heating during the period from 1 to 4 hours; (e) the magnetic particles obtained in step (d) are submitted to a secondary washing by decanting, dialysis or filtration, with addition of deionized water and organic solvents, removing the excess functionalizing agents; (f) the material obtained in step (e) is submitted to a controlled drying step, through hypercritical drying, freeze-drying or spray drying, in which the functionalized magnetic gel is transformed in a functionalized nanoparticulate powder; (g) the functionalized nanoparticulate powder obtained from step (f) is packed, preferably in an airtight plastic, in order to be commercialized as powder, or dispersed in a solvent and bottled to be commercialized as ferrofluid.