A new aerosol dynamical box model, Ion-UHMA (University of Helsinki Multicomponent Aerosol model for neutral and charged particles), is introduced in this paper. The model includes basic dynamical processes (condensation, coagulation and deposition) as well as ion–aerosol attachment and ion–ion recombination. The formation of particles is treated as model input or, alternatively, the model can be coupled with an existing nucleation model. Ion-UHMA was found to be able to reproduce qualitatively the measured time evolution of the particle number size distribution, when the particle formation and growth rates as well as concentrations of particles > 20 nm in diameter were taken from measurements. The simulated charging state of freshly formed particles during a new particle formation event evolved towards charge equilibrium in line with previously-derived analytical formulae. We provided a few illustrative examples to demonstrate possible applications, to which the Ion-UHMA model could be used in the near future.