The present invention relates to an improved process for the preparation of Tenofovir Disoproxil and its pharmaceutically acceptable salts comprising the steps of: a) esterifying Tenofovir with chloromethyl isopropyl carbonate in presence of a base, phase transfer catalyst and optionally dehydrating agent, in a suitable solvent; b) optionally purifying Tenofovir Disoproxil; and c) converting of Tenofovir Disoproxil into its pharmaceutically acceptable salts. The present invention further relates to a process for the preparation of Tenofovir by reacting 1-(6-amino-purin-9-yl)-propan-2-ol with toluene-4-sulfonic acid diethoxy phosphoryl methyl ester in presence of a base in a non-polar solvent medium followed by hydrolysis.