The present process provides an improved method for the preparation of 4-amino-1-((2R,3R,4R,5R)-3-fluoro-4-hydroxy-5-hydrox-ymethyl-3-methyl-tet- rahydro-furan-2-yl)-1H-pyrimidin-2-one of the formula (IV) which is a potent inhibitor of Hepatitis C Virus (HCV) NS5B polymerase. ##STR00001##