The results of measurement of surface potential gradient of the atmosphere in Kolkata (latitude: 22°34′ N) will be presented. The observed fields at daytime and night time are seen to be higher and show considerable fluctuations from the daily averages of electric field and also a few hours difference in phase with the observations made at different tropical and temperate latitudes. The mean value of the potential gradient averaged for 35 days over a period from February 2004 to January 2005 is around 200 Vm-1 and the maximum and minimum values are 1.14 times and 0.88 times the mean value, respectively. The results are discussed in terms of the variations of the local factors as well as distribution of thunderstorm activities. © 2006 IACS.