Annealing tests in an oxidizing gas were carried on steel specimens of wire rod grades. The rate of decarburization increases with the annealing temperature and the carbon content of the steel according to an exponential law in the time ranges which, in turn, follows the parabolic law. Results are also included to show the influence of time and temperature on scale formation and internal oxidation, weight gain due to scale, optimum annealing temperatures and precipitates due to oxidation.