The present invention relates to a novel and easily scalable process for the preparation of pure Liothyronine Sodium, i.e., Sodium (S)- 2-amino-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]propanoate or (S)-2-Amino-3-[4-(4-hydroxy-3,5-diiodophenoxy)-3,5- diiodophenyl]propanoic acid sodium salt. The present invention provides an industrially feasible, cost effective process involving the use of commercially available, simple raw materials in the process. The process of the present invention is easily adaptable for multi kilo manufacturing plants for scaling-up the most demanding API product Liothyronine sodium at a very cheap cost, compared to the current import costs of the material and contemporary technologies in vogue. Liothyronine is ideally used for the treatment of thyroid hormone deficiencies such as hypothyroidism. [Formula I]
