In this work, we have attempted to explore whether the nucleophilicity equalization principle can be conceived analogous to the well-established electronegativity, hardness, and electrophilicity equalization principle. Based on our new definitions of hardness and electronegativity and relying upon the geometric mean principle we proposed a new electronic structure principle, namely the nucleophilicity equalization principle. This approach provides a unified and useful procedure to calculate the nucleophilicity of molecules and groups assuming that nucleophilicity equalization principle is operative and justifiably valid. The results shown here indicate a close resemblance between theory and experiment. (C) 2016 Elsevier B.V. All rights reserved.