Abstract: An improved process for the preparation of ceftriaxone sodium comprising the steps of: i) reacting the 3-cephem derivative of formula (II) ?with halo acid derivative of formula (III) ?wherein X represents halogen and Y represent halogen in the presence of silylating agent and methylene chloride at ?25 to 10° C., to produce (IV), ii) quenching the reaction by pouring the reaction mixture into water or in a aqueous solution of sodium carbonate, iii) preparing sodium salt solution of (IV) by adding sodium carbonate and separating the organic layer, iv) cyclizing the sodium salt of (IV) in the aqueous solution with thiourea at a temperature in the range of 0 to 30° C., v) adjusting the pH to 1.5 to 2.5 to precipitate the ceftriaxone free acid, vi) converting the ceftriaxone free acid to sodium salt using sodium-2-ethyl hexanoate in water and vii) precipitating and isolating the ceftriaxone sodium.