During the summer of 2005, concentrations of surface ozone (O(3)), oxides of nitrogen (NO(x)), respirrable suspended particulate matter (RSPM) and total suspended particulate matter (TSPM), relative humidity (RH), wind speed (WS) and wind direction (WD) were collected over successive periods of about 24 h at five sites. UV photometric ozone analyzer was used to measure the concentration of surface O(3). The study deals with the characteristics of hourly and daily mean surface O(3) under different climatic conditions, such as temperature, relative humidity, wind speed and wind direction and other pollutant concentrations. The maximum hourly O(3) concentration reached 53 ppb on 17th May. The ground-level O(3) concentration in Chennai varied between 2 and 53 ppb. The concentration of NO(x) and O(3) were below the prescribed limits. The TSPM values were exceeded the National Ambient Air Quality Standards (NAAQS) at Koyambedu, Mandaveli, Taramani and Vallalar Nagar study area.