The temperature history for the BPI-W2 well in the oil-producing Suphan Buri Basin, central Thailand, has been investigated using different surface temperatures (T-s). Two ID models using T-s values of 0 degrees C and similar to 22 degrees C were able to fit the suppression-corrected vitrinite reflectance (VR) values and burial peak temperatures (T-peak) in the well. The geothermal gradient averaged over 3 km is similar to 54 degrees C/km for T-s = 0 degrees C, whereas it is similar to 42 degrees C/km for T-s similar to 22 degrees C. T-s = 0 degrees C is, however, considered to be unrealistic and the similar to 54 degrees C/km gradient is therefore too high. Similarly, a previously determined geothermal gradient of 62 degrees C/km is considered to be an overestimate. The geothermal gradient of similar to 42 degrees C/km is plausible compared to other geothermal gradients onshore and offshore Thailand, although it is at the low end. This may be due to a too low suppression correction for the measured VR values. The obtained temperature history can be used to predict measured present-day temperatures of T-s similar to 22 degrees C and 77 degrees C in the reservoir in the U Thong oilfield. The obtained temperature history associated with the geothermal gradient of similar to 42 degrees C/km seems realistic as it predicts that the onset of oil generation at 107 degrees C will have post-dated reservoir and trap formation in Middle to Late Miocene times.