NOAA satellites and the orbiting Solar and Heliospheric observatory (SOHO) recorded one of the most powerful solar flares of the previous solar cycle 23 on 14 July 2000. This intense X 5 –class flare was erupted from sunspot region 9077 at 1024 UT. Simultaneously the coronagraph on board the SOHO recorded a ‘full-halo’ coronal mass ejection (CME) aimed toward the Earth. As CME’s are gigantic bubbles of electrified gas carrying away as much as 10 billion tons of solar material, such a release of solar particles produced very intense geomagnetic disturbances and further modulates the cosmic ray intensities. In this study an attempt has been made to analyze the influence of this space radiation storm on Earth’s geomagnetic field as well as on the cosmic ray intensity variation. as reflected b a strong Forbush decrease event. We have used the geomagnetic indices Dst, Ap and AE and for cosmic rays the data from Calgary NM 64 (geographic Lat. North 51.08, Long. East 245.87, cut off rigidity 1.09 GV) is used. The study revealed that event is well correlated with the Forbush decrease and producing significant depressions in the geomagnetic indices. We have obtained the encouraging results that are discussed in the detailed paper.