Results of field measurements carried out from June 15 to December 31, 1995, in Córdoba city (Argentina) are presented. During this field campaign, surface ozone mixing ratios were generally around 30-35 ppb (afternoon peak). However, during the first week of September, days with excessive ozone values close to 100 ppb were found. These elevated ozone concentrations appeared together with high values of NOx, CO, PM10, and an unusual meteorological situation for this time of the year. These results made this episode an interesting one to be studied in more detail. In this work, we used chemical and meteorological data to trace the region from where the assumed precursors were emitted and we identified possible source characteristics.