We describe spatial and temporal variations in the partial pressure of carbon dioxide (pCO2) in the central and western equatorial Pacific on the basis of measurements conducted for the periods between 1987 and 1994. Surface water pCO2 data indicate the significant differences in longitudinal distribution depending on the ocean conditions. We examine the relationship between the area showing higher surface pCO2 values and the El Ni¿o/Southern Oscillation phenomenon by using the Southern Oscillation Index. Results indicate that the area showing higher surface pCO2 values correlates with the SOI, which suggests significant intra-and interannual fluctuations of CO2 outflux from the central and western equatorial Pacific. ¿ American Geophysical Union 1996