A novel method was introduced to investigate oxidation behavior of melts in different conditions such as flux, alloying element, atmosphere, etc. This approach was based on rheology properties of melts, in which by tracing viscosity variations during oxidation, the behavior of melt can be explored. A modified falling ball viscometer was proposed and used for viscometry. Oxidation of aluminum and Al-Mg alloys was studied using this method. According to the results, it was found that this method was not only a proper approach for investigating oxidation behavior but also could be used as a compliment along conventional approaches.