Response of low latitude ionosphere to the geomagnetic storm of May 2005 has been studied using total electron content (TEC) data obtained from the global positioning system (GPS) receivers. This study was carried out using the receivers that are located near the northern crest (~ 15° N mag. Lat.) of the equatorial ionization anomaly from 55° E to 105° E longitudes. These studies have been substantiated with the ground based magnetometer data at Alibag and Tirunelveli, a low latitude and equatorial station, respectively. The TEC on May 15 reveals two well defined humps as well as TEC modulations. These enhancements have been attributed to the prompt penetration electric fields and delayed equatorial plasma fountain. The traveling atmospheric disturbance (TAD’s) has also been inferred from the low amplitude modulations in the TEC. The solar wind parameters, southward component of inter planetary magnetic field, cross polar cap potential drop, zonal component of the inter planetary electric field and the strength of the equatorial electrojet has also been analyzed for the complete study of disturbed ionospheric conditions.