An organic-inorganic composite, poly-o-anisidine Sn(IV) phosphate, was chemically synthesized by mixing ortho-anisidine into gels of Sn(IV) phosphate with different mixing volume ratios. Studies on the effect of eluant concentration, elution behavior and separation of metal ions were carried out to understand the ion-exchange capabilities. Due to Cd(II) selective nature of composite, revealed by distribution studies, Cd(II) ion selective membrane electrode was fabricated. The analytical utility of the electrode was established by employing it as an indicator electrode in electrometric titrations having fast response time, 3–5s, and long life span of six months. Some physical parameters like self-diffusion coefficient (D0), activation energy (Ea) and entropy of activation (ΔS0) have been evaluated under conditions favoring a particle diffusion-controlled mechanism by studying ion-exchange kinetics.