In this report, the analytical expression of Coulombic interaction between a spherical nanoparticle and a tetragonal nanorod is derived. To evaluate the Coulombic interaction in the oriented attachment growth of tetragonal nanorods, we analyze the correlation between the Coulombic interaction and the important growth parameters, including: nanoparticle–nanorod separation, aspect ratio of the nanorods, and surface charge density. Our work opens up the opportunity to investigate interparticle interactions in the oriented attachment growth of tetragonal nanorods. To evaluate the Coulombic interaction in the oriented attachment growth of tetragonal nanorods, we analyze the correlation between the Coulombic interaction and the important growth parameters, including : nanoparticle-nanorod separation, aspect ratio of the nanorods, and surface charge density. Our work opens up the opportunity to investigate interparticle interactions in the oriented attachment growth of tetragonal nanorods.