Present study deals with the synthesis, characterization and corrosion inhibition effect of a hexafunctional cyclotriphosphazene derivative, namely 2,2,4,4,6,6-hexakis(oxiran-2-ylmethoxy)-1,3,5,2 delta, 4 delta,6 delta-triazatriphosphinine(HPGCP)for copper in 3 wt% NaCl medium. The synthesized HPGCP was characterized using numerous spectral techniques such as H-1, C-13, P-31 NMR (Nuclear magnetic resonance) and Fouriertransform infrared spectroscopy (FT-IR) methods. Anti-corrosive effect of the HPGCP was measured using electrochemical and computational methods. Results showed that HPGCP exhibited highest protection efficiency of 95% at as low as 10(-3) M concentration. Polarization studies showed that HPGCP acted as mixed type inhibitor and its adsorption obeyed the Langmuir adsorption isotherm model. Density Functional Theory (DFT) based computational studies demonstrate that HPGCP interacts with copper surface using donor-acceptor interactions inwhich three nitrogen atoms and six p-electrons of the cyclotriphosphazene ring play significant role in metalinhibitor interactions. Molecular dynamic (MD) simulations study demonstrated that HPGCP spontaneously interacts withmetallic surface using its electron rich centers and acquires the planar orientation. Experimental results were well corroborated with the computational results. (C) 2020 Elsevier B.V. All rights reserved.