Pyrazole and Thiazole are azoles which are a group of five membered heterocycles with two heteroatoms in the ring. These heterocycles comprise various pharmaceuticals having antitumor, anticancer, anti-HIV activities [1-5]. Heterocycles based efficient solar cells, organic semiconductors and electronics have also been receiving attention in recent years [6,7]. These compounds are highly reactive towards electrophilic attack. These substitution reactions seem important because of uses of these derivatives in synthetic and pharmaceutical intermediates [8-10]. Some of the halogenated derivatives are biologically active against various fungi and bacteria [11]. It therefore seems significant to study the kinetics of such halogenation reactions so that the quantitative assessment of relative reactivity can be determined. The kinetics of bromination of some five membered heterocycles such as imidazole, pyrazole and thiazole etc. have already been studied using brominating agents [12]. In view of the above, it is envisaged to study the kinetics of pyrazole and thiazole using two halogenating agents, molecular iodine and molecular chlorine. The reactions are too rapid to be studied by any conventional technique. Hence the present study is carried out by using a simple yet efficient technique, namely hydrodynamic voltammetry [13-15]. The data obtained by this study would be useful to assess the reactivity of two heterocycles with respect to two halogenating agents, which was lacking hitherto.