A kinetic model for the oxidation of selenium and tellurium in the molten bath of an industrial Kaldo furnace during the refining step is presented in this article. During plant experiments, samples of the molten metal were collected hourly and chemically analyzed for selenium, tellurium, and silver. Selenium oxidized from the beginning of the refining step, whereas oxidation of tellurium only occurred until the Se/Te mass ratio decreased to a value of 0.55. Good agreement between the model predictions and the experimental data was obtained.