The performance of ab initio methods (MP2, DFT/B3LYP, random-phase approximation (RPA), CCSD(T) and QCISD(T)) in predicting interaction energy of X-H ... pi (X-H = HCCH, HCl, HF; pi = C2H2, C2H4, C6H6) hydrogen complexes are assessed systematically. The CCSD(T)/CBS benchmarks of interaction energy are reported. It is found that RPA agrees well with CCSD(T)/CBS benchmarks and experimental results. CCSD(T) and QCISD(T) perform the best only when compared with CCSD(T)/CBS benchmarks, MP2 performs well only for experimental data. B3LYP provides the worst accuracy. Additionally, the equilibrium structure, interaction type of X-H ... pi hydrogen complexes are investigated by the natural bond orbital (NBO) and the non-covalent interaction index (NCI). (C) 2018 Elsevier B.V. All rights reserved.