Detection of improvised explosives such as triacetonetriperoxide (TATP) requires detailed knowledge of its chemical and physical properties. Electronic structure calculations were employed to study the properties of the explosives TATP and diacetonediperoxide (DADP). The calculated results were compared to available experimental data. The lowest energy structure, vibrational spectrum and thermal decomposition mechanism of TATP were examined. The applicability of these theoretical methods was demonstrated by the agreement between the experimental data and the calculated ground state structure as well as the vibrational IR and Raman spectra. The thermal decomposition pathway of a TATP molecule was investigated by a series of calculations aimed to identify the transition states along the decomposition pathway, the associated intermediate fragments and the final decomposition products. The initial chemical events that take place during detonation of bulk triacetonetriperoxide were studied by additional calculations were based on molecular dynamics (MD) simulations. In these simulations a reactive force field was used, which has been extended to reproduce the quantum mechanics (QM)-derived relative energies of the reactants, products, intermediates and transition states related to the TATP unimolecular decomposition.