The present invention relates to a method for the preparation of citalopram comprising reaction a compound of formula (I) with a compound having the formula wherein X is a suitable leaving group and R is —CH2—O—Pg, —CH2—NPg1Pg2, —CO—N(CH3)2, —CH(OR1)(OR2), —C(OR4)(OR5)(OR6), —COOR3, —CH2—CO—NH2, —CH═CHR7 and —CONHR8, wherein Pg is a protection group for an alcohol group, Pg1 and Pg2 are protection groups for an amino group, R1 and R2 are independently selected from alkyl, alkenyl, alkynyl and optionally alkyl substituted aryl or aralkyl groups or R1 and R2 together form a chain of 2 to 4 carbon atoms, each of R3, R4, R5, R6 and R7 are independently selected from alkyl, alkenyl, alkynyl and optionally alkyl substituted aryl or aralkyl and R8 is hydrogen or methyl; to form a compound of the formula wherein R is as defined above; followed by conversion of the R group and isolation of citalopram base or a pharmaceutically acceptable salt thereof.