The Fischer-Tropsch synthesis process is a polymerization reaction in which various chain lengths of product can be produced from a mixture of CO and H-2 (synthesis gas). A solvothermal technique was used to synthesize magnetic iron cobalt cerium mixed oxide nano particles. Process variables such as reaction temperature and time can play an important role in a chemical process. The results showed that the optimal preparation time and temperature in order to enhance light olefin (C-2-C-4) selectivity is 18 h and 120 degrees C. The effects of experimental variables including temperature (120, 150, 180 degrees C) and reaction time (10, 14, 18 h) were investigated. The nanoparticles were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), temperature programed-reduction (TPR), Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), and X-ray photoelectron spectroscopy (XPS). Average crystalline size determined from XRD patterns ranged over 4.5-8.3 nm. The results indicate that reaction temperature and time have marked effects on the magnetic properties of nanoparticles changing from a ferromagnetic behavior to a superparamagnetic one at a reaction temperature of 120 degrees C. TPR profiles of the nanoparticles synthesized at different temperatures revealed that reducibility shifted to higher temperatures. XPS results verified Fe3+, Co2+, and Ce3+ of oxidation states.