The present work describes a convenient and efficient approach for the synthesis of bifunctional chelating agent, 1-(p-aminobenzyl)ethylenediaminetetramethylphosphonic acid (Am-Bz-EDTMP). The key steps involved are functionalization of L-phenylalanine to give ethylenediaminetetraacetic acid derivative and its conversion to phosphonic acid followed by the reaction with NHS-folate to give 1-(p-aminobenzyl)EDTMP-folate conjugate to be used for targeted radio imaging and therapy. Radiolabeling with In-111 and Sm-153 of Folate-Bz-EDTMP conjugate showed very high stability under physiological conditions.