The [H2–HCO]+ complex is likely to be one of the most important complexes in interstellar space, as it is a complex of the most abundant interstellar species. In the current work, we investigate the interaction energy and potential surface of the complex using a range of computational methods. The dynamics of the complex are investigated by incorporating an external time-dependent field into Car-Parrinello molecular dynamics (CPMD) and inducing a vibrationally activated dissociation. This excitation method is compared to a normal-mode excitation from the equilibrium structure. The results agree well with the available experimental data: an excitation to the first vibrationally-excited state of either of the high-frequency HCO+ modes (ν2, ν3) causes a dissociation of the complex on picosecond timescales.