Size-controlled cadmium nitroprussides, with particles in the micron meter or submicron size range (0.050–1.15 micron), (CdNPs) were prepared from total and varied compositions of water and formamide solvent in the complexation reaction of cadmium and nitroprusside ions. Four analytical systems (CdNP-1, CdNP-2, CdNP-3, and CdNP-4) were set up. The coordinated materials were investigated by spectroscopic and analytical techniques such as Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and cyclic voltammetry (CV). The CVs of the modified graphite paste electrode with CdNP-1, CdNP-2, CdNP-3, and CdNP-4 (10% m/m) exhibited a defined redox pair with formal potential (Eθ′) = 0.63 ± 0.02 V (ν = 20 mV s−1; KNO3 1.0 M). The dependence of particle size on the isoniazid electro-oxidation was verified by CdNP-3 and CdNP-4 microparticles.