The surfactant flooding is a commonly enhanced oil recovery (EOR) process to reduce the interfacial tension (IFT) between water and crude oil and recover the residual oil of reservoir.  However, the efficiency of surfactant flooding is affected by the adsorption of the chemical in the porous medium and the interfacial tension water/crude oil is not reduced enough to have an effect on trapped oil. As a result, the simultaneous use of surfactant and nanoparticles is presented as a promising alternative to improve the chemical flooding in EOR processes. Some of the advantages of the simultaneous use of surfactants and nanoparticles in EOR processes are the increase in the efficiency of injection fluid for sweeping, the reduction of the adsorption of surfactant onto reservoir rock, the alteration of wettability and the reduction of water/crude oil interfacial tension. However, the large amount of nanoparticles that would be used in CEOR process can limit their application. Therefore, the main objective of this work is to synthesize, characterize and evaluate magnetic iron core-carbon shell nanoparticles for the reduction of interfacial tension between brine and crude oil and its effect in oil recovery, which can be recovered and re-used after application due to its magnetic properties. The magnetic iron core-carbon shell nanoparticles were obtained following a new one-pot hydrothermal procedure and were carbonized at 900 °C using a teflon-lined autoclave. The core-shell nanoparticles were characterized by scanning electron microscopy (SEM), Dynamic light scattering (DLS), N₂ physisorption at -196 °C, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetometry measurements. Magnetic iron core-carbon shell nanoparticles with an average particle size of 60 nm and a surface area of 175 m^2·g^-1 were obtained. The XPS spectrum corroborated that magnetic Fe (0) of the core was adequately coated with a carbon shell. The interfacial tension was evaluated using a spinning drop tensiometer for a medium viscosity crude oil and a surfactant mixture, showing a reduction of the interfacial tension approximately to 1×10^-4 mN∙m^-1 at a nanoparticles concentration of 100 mg∙L^-1. At this nanoparticles concentration, the dynamic adsorption tests demonstrated that the nanoparticles reduce 33% the adsorption of the surfactant in the porous medium. The simultaneous effect of core-shell nanoparticles and surfactant in the displacement test under reservoir conditions was performed obtaining oil recovery values up to 98%. The magnetic iron core-carbon shell nanoparticles synthesized and evaluated in this research represents a novel nanomaterial that takes advantage of the magnetism of Fe in metallic state and the high availability of the carbon for obtaining ultra-low IFT and increase oil recovery.