Hyperthermia is one of the most recents therapies for cancer treatment using particles with nanometric size and appropriate magnetic properties for destroying cancer cells. Magnetic nanoparticles (MNP's) of Fe-Ga and synthesized using a polycondensation reaction by sol-gel method were obtained. MNP's of Fe(1.4)Ga(1.6)O(4) that possess an inverse spinel structure were identified by X-Ray Diffraction, Transmission Electron Microscopy, Scanning Electron Microscopy and Energy Dispersive Spectroscopy. The results showed that the MNP's are composed only by Fe, Ga and O and their size is between 15 and 20 nm. The magnetic properties measured by Vibration Sample Magnetometry demonstrated a saturation magnetization value of 37.5 emu/g. To induce the MNP's bioactivity, a biomimetic method was used which consisted in the immersion of MNP's in a Simulated Body Fluid (SBF) for different periods of time (7, 14 and 21 d) along with a wollastonite disk. The formation of a bioactive layer, which closely resembles that formed on the existing bioactive systems and with a Ca/P atomic ratio within a range of 1.37-1.73 was observed on the MNP's. Cytotoxicity of MNP's was evaluated by in vitro hemolysis testing using human red blood cells at concentrations between 0.25 and 6.0 mg/mL. It was found that the MNP's were not cytotoxic at none of the concentrations used. The results indicate that Fe-Ga MNP's are potential materials for cancer treatment of both hard and soft tissue by hyperthermia and drug carriers, among other applications.