Quantum chemical calculations were carried out to explore the effects of substituents in para position of aniline as well as phosphine on the strength of interactions in pnicogen-bonded (PB) complexes of the 4-XPhNH2:PFnH3-n (n=1–3 and X=H, F, CN, CHO, NH2, CH3, NO2 and OCH3). The P⋯N pnicogen bond strength in these complexes was examined at M06-2X/6–311++G(d,p), MP2/6–311++G(d,p), MP2/cc-pVDZ, CCSD/cc-pVDZ and MP2/aug-cc-pVTZ levels of theory. The dispersion corrected M06-2X-GD3, B2PLYP-GD3 and mPW2PLYP-GD2 functionals were also used to calculate the binding energies. The changes in the pnicogen bond strength due to the change of the substituents were well monitored by the changes in the interaction energy, structural parameters, natural charge, charge transfer, electron density topology, NMR chemical shielding and spin-spin coupling constants. The BSSE-corrected BEs change from 14.5 to 21.4kJmol−1 for the 4-XPhNH2:PF3, 21.5 to 30.5kJmol−1 for the 4-XPhNH2:PF2H and 24.2 to 33.1kJmol−1 for the XPhNH2:PFH2 complex at MP2/aug-cc-pVTZ level and 12.5 to 18.9kJmol−1 for the 4-XPhNH2:PF3, 17.4 to 26.5kJmol−1 for the 4-XPhNH2:PF2H and 18.9 to 26.5kJmol−1 for the XPhNH2:PFH2 complexes at MP2/6–311++G(d,p) level. For each PFnH3-n monomer, results demonstrated that the strength of the pnicogen bonds increases by introducimg electron-donating substituents in 4-XPhNH2 molecule, whereas a reverse situation was found upon introducing electron-accepting substituents. Natural bond orbital analysis confirmed that the charge transfer takes place from 4-XPhNH2 to PFnH3-n. Electron density properties based on atoms in molecules theory were also utilized to characterize the pnicogen bonds.