According to the resonance assisted hydrogen bond (RAHB) theory, the π-electron delocalization (π-ED) promotes the intramolecular hydrogen bond (IMHB). Since the relation between the IMHB and π-ED are not well known, in the present work, the linear correlations between the descriptors of π-ED and estimated IMHB energies were systematically investigated. In this regard, the significance of π-ED in chelated forms of the benchmark systems by various descriptors, such as λ, λ′, HOMA, NICS, PDI, ATI, FLU and FLUπ were evaluated. On the other hand, the IMHB energy of RAHB units by some adopted models, such as RRM, RBM, GCM, IRM and OCM are estimated. Furthermore, we explored all of the possible linear correlations between the π-ED indices and various IMHB energies to judge about the performance of RAHB theory. According to our results, it was found that there are great liner correlations between the RRM, RBM and GCM than IRM and OCM methods with some of the π-electron delocalization indices;RRM: λ′>FLU>λ>HOMA>FLUπ≈ATI>PDI>NICS(1)>NICS(0)RBM: λ′>λ>HOMA>FLU>FLUπ>ATI>PDI>NICS(1)>NICS(0)GCM: λ′≈HOMA>λ>PDI>FLU>FLUπ>NICS(1)>ATI>NICS(0).Surprisingly, the bond order factor of Gilli (λ′), which introduced similar to λ, has the best linear relationship with the IMHB energies. Consequently, the linear coefficients between the RRM, RBM and GCM energies with HOMA, λ and λ′ descriptors are in agreement with the RAHB theory.