An experimental study has been conducted to investigate three-phase flow effects on oil recovery during a steam flooding process (in the case of nondistillable white oil). A laboratory setup has been developed to simulate field conditions. The experiments were performed using a linear model packed with sand. The first step of this work consisted in a hot water flooding, the results of which showed an increase in oil recovery and a reduction in residual oil saturation when increasing temperature. The same core, previously flooded by hot water, was flooded again by steam. In this case, we obtained an additional oil recovery that was attributed to three-phase flow effects rather than a contribution of vaporization/condensation effects. To check this hypothesis, we performed the same experiment, but at the last stage we replaced steam by nitrogen. The experimental results showed that the additional oil recovery after nitrogen injection was basically independent of the temperature, and comparable to the one obtained after steam injection. Finally, the experimental results have been compared with numerical results, for both hot water and steam injection.