Accurate fuel combustion modelling is a matter of immense importance to design clean combustors and reduce greenhouse gas emissions and pollutants. In this Brief Communication, we present the effects of internal dynamics of one n-heptane molecule which are controlling chemical kinetics of hydrogen abstraction reactions through multi-pathway reaction dynamics. It is established that the slope of Arrhenius plots dramatically changes in comparison with the harmonic single static pathway approach in the temperature range of 200–3000 K. We apply a combination of the multiple conformation statistical thermodynamic approach and variational transition-state theory (VTST) to obtain dynamic multi-path rate coefficients (kMP-T-VTST and kMP-LH-VTST). Compared with single-path VTST (kSP-H-VTST) results, the thermal reaction rate coefficients obtained from our MP-VTST calculations differ considerably due to the fact that tunnelling and cross-conformational effects in the reactions, and the anharmonic and quasi-harmonic contributions in multiple conformer molecules cannot be ignored or simplified.