Aims. The properties of the Galactic supernova remnant (SNR) RX J0852.0-4622 are theoretically analysed.Methods. An explicitly time-dependent, nonlinear kinetic model of cosmic ray (CR) acceleration in SNRs is used to describe the properties of SNR RX J0852.0-4622, the accelerated CRs, and the nonthermal emission. The source is assumed to be at a distance of ≈1 kpc in the wind bubble of a massive progenitor star. An estimate of the thermal X-ray flux in this configuration is given. Results. We find that the overall synchrotron spectrum of RX J0852.0-4622 as well as the filamentary structures in hard X-rays lead to an amplified magnetic field B > 100 μG in the SNR interior. This implies that the leptonic very high energy (VHE) γ-ray emission is suppressed, and that the VHE γ-rays are hadronically dominated. The energy spectrum of protons produced over the lifetime of the remnant until now may well reach "knee" energies. The derived γ-ray morphology is consistent with the HESS measurements. The amount of energy in energetic particles corresponds to about 35% of the hydrodynamic explosion energy. A remaining uncertainty concerns the thermal X-ray flux at 1 keV. A rough estimate, which is possibly not quite appropriate for the assumed wind bubble configuration, is found to be higher than the nonthermal flux at this energy. Conclusions. It is concluded that this SNR expanding into the wind bubble of a massive star in a dense gas environment can be a hadronic γ-ray source that is consistent with all existing multiwavelength constraints, except possibly the thermal X-ray emission.