Complexation of therapeutic compounds with metals present in human body in trace amount may influence their nature, properties and pharmacokinetics. Electrochemical studies on complexes of cobalt with antihypertensive drug, Atenolol [RS, 4-{2-hydroxy-3-isopropylaminopropoxy}phenylacetamide] have been carried out at dropping mercury electrode. Direct current polarographic technique has been employed to study the process. It is found that reduction of Co(II) at d.m.e was irreversible in aqueous medium. Succesive addition of drug shifts half wave potential of cobalt, towards more negative direction. As the system is found to be irreversible and diffusion controlled hence kinetic parameters (K0fh, an) have been calculated using Gaur-Bhargav as well as Meites-Israel method at different temperatures. Results obtained by these methods are in good agreement with each other.