We report detailed numerical studies for bound and resonance states of HO2 using a time-dependent (TD) wave packet approach. The energies of bound and resonance states are calculated from an energy spectrum which is obtained by time-->energy Fourier transform of the autocorrelation function. Numerous bound and resonance (both inelastic and reactive) states are identified and their energies are obtained, all from a single wave packet calculation. We employed a Gaussian function to generate the Gaussian spectrum which is defined by convoluting the autocorrelation function with a Gaussian weighting function in the time-->energy transform. As shown in a previous paper, the Gaussian spectrum is positive definite and each spectral peak corresponds to a true eigenenergy which makes the picking of eigenenergies straightforward. The wave functions of highly excited bound states and essentially all resonance states show complicated nodal patterns and their spectroscopic assignments seem to be impractical. Our calculated energy spectrum above the reaction threshold shows similar structures as the energy dependence of the reaction probabilities obtained from a previous reactive scattering wave packet calculation. The DMBE IV potential energy surface (PES) of Varandas and co-workers is used in the present calculation.