The effect of the presence of platinum on the surface of SO42--ZrO2 was studied. The addition of platinum neither produces significant changes in the textural properties of SO42--ZrO2 nor interferes in the process of crystalline structure formation. After calcining, the presence of platinum allows the retention of a higher sulfur concentration. When calcination takes place at 600 degrees C, SO42--ZrO2, with or without platinum, shows S6+ species on the surface, but only when platinum is present does a small amount of SO species appear. At the same calcination temperature, platinum is found in the metallic state. Therefore, the SO species could be associated with platinum by modifying its metallic properties.