The experimental electron density of bis(tiosemicarbazide)zinc(II) dinitrate complex, [Zn(CH5N3S)2](NO3)2, was studied. The Hansen-Coppens multipole model was used to extract the electron density from high resolution X-ray diffraction data collected at 100 K. Careful strategies were designed for the electron density refinements regarding the charge transfer between the anionic and cationic parts of the complex. Particular attention was also paid to the treatment of the electron density of the zinc atom interacting with two thiosemicarbazide ligands in a tetrahedral coordination. Nevertheless, the filled 3d valence shell of Zn was found unperturbed and only the 4s shell was engaged in the metal-ligand interaction. Topological properties of both electron density and electrostatic potential, including kinetic and potential energy densities, and atomic charges were reported in order to quantify a metal-ligand complex with particular Zn-S and Zn-N bonds and hydrogen bonding features. Chemical activities were screened through the molecular surface on which the 3D electrostatic potential function was projected. The experimental results were confronted to those obtained from gas phase quantum calculations and a good agreement was reached between these two approaches. Finally, among other electrostatic potential critical points, the values at the maxima corresponding to the nuclear sites were used as indices of the hydrogen bonding capacity of the thiosemicarbazide ligand.