The oil and gas sector has recently shown an interest in hydrodynamic cavitation for oil enhancement, as it allows reducing transportation and refinement costs. This work presents a fluid-dynamic study of Colombian oil at different temperatures passing through a vortex reactor. First, an experimental design was elaborated, establishing the temperature and quantity of the injected hydrogen donor as factors and the final viscosity of oil as the response. Then, a numerical model was developed in the Ansys Fluent software using multiphase models, where the required properties of the fluid were obtained via laboratory tests and the Aspen HYSYS software. The results obtained from numerical experimentation were analyzed, and it was observed that the final viscosity was less affected by the temperature than by the hydrogen donor. Moreover, numerical modeling showed an exponential relation between vapor generation and temperature. The experimental and numerical data were compared, and it was found that the temperatures established in the experimental design were not high enough to generate a significant amount of vapor, which is why the decrease in viscosity was lower.