The production rate of oil reservoirs decreases gradually as reservoir pressure drops. This would occur due to various reasons, among them the precipitation and deposition of asphaltene. In this study, the impacts of two nanoparticles of titanium oxide and iron oxide with various concentrations were investigated for retarding the precipitation of asphaltene in the process of CO2 injection into synthetic oils. The experimental interfacial tension results clearly showed that both nanoparticles can effectively impede the precipitation of asphaltene. This has been sought in terms of change in the slope of interfacial tension curves. In this process, the adsorption of asphaltene by nanoparticles and interaction with precipitated asphaltenes at the interface between the two fluids were imperative in terms of adsorption capacity and affinity. The comparison of these two nanoparticles also revealed that Fe3O4 nanoparticles were more effective than TiO2 for reducing the precipitation of asphaltene at the interface between CO2 and oil and intensified the miscibility of CO2 into oil. Furthermore, the optimum weight fraction of both nanoparticles was found to be 1.0%. Finally, the reduction of the asphaltene precipitation intensity for the optimum concentration for oil solutions containing TiO2 and Fe3O4 nanoparticles was 17 and 18%, respectively.