The electrochemical sensing of Nalbuphine hydrochloride drug substance in vitro by the cyclic voltammetry technique using the activated glassy carbon electrode. The solvation of CdCl₂ alone or in the presence of Nalbuphine HCl was studied by CV technique in 0.05 M KCl supporting electrolyte and different concentrations from CdCl₂ at 305.15K. The cyclic voltammograms were preceded at different scan rates 0.1, 0.05, 0.02 and 0.01 V Sec^-1. Also, different Nalbuphine HCl concentrations were utilized for studying their effect as electrochemical sensors on the solvation and kinetics parameters of CdCl₂. The redox mechanism of the system was determined from the resulted data. Moreover, the Gibbs free energies of the complex formation were evaluated. The formation constants and Gibbs free energies were calculated from the conductometric titration curves. The molar ratios of the complexes were obtained indicating the formation of 1:2 and 1:1 (M:L). The formation constants of different complexes in water: methanol solvent followed the order: K_f (1:2) > Kf (1:1) for (M:L). The (∆H) and (∆S) of formation and association of complexes were also estimated and discussed. The solvation ∆G^o, ∆Hs and ∆Ss were calculated from solubility measurements for nalbuphine HCl at different temperatures.