The present investigation is about the determination of the gas phase concentration parameters of the notorious explosives triacetone triperoxide (TATP, 1) and diacetone diperoxide (DADP, 2), which have been frequently used in improvised explosive devices. According to calculations with EXPLO5 the energetic performance of both explosives is similar. The enthalpy of sublimation Delta(g)(cr)Eta(o)(m) (298.15K) (1: 76.7 +/- 0.7 kJmol(-1); 2: 75.0 +/- 0.5 kJmol(-1)) and vapor pressures p(sat)(298.15K) (1: 6.7Pa, 2: 26.6 Pa) of both compounds have been studied using the transpiration method in the ambient temperature range of 274-314K. The results obtained in this work were compared critically with the existing literature values. Data for DADP (2) mostly shows agreement with literature ones. However data of TATP (1) obtained in this work revealed insufficient agreement of all sets of data available in literature, which might be explained by the rich polymorphism of TATP 1. The saturation and diffusion equilibrium concentration of both analytes was calculated at 298.15K. In comparison to the saturation equilibrium concentration measured in this work (1: 600gL(-1), 2: 1589gL(-1)) the corresponding estimated diffusion condition air concentrations (1: 3.1ngL(-1), 2: 10ngL(-1), for a surface of 200cm(2)) are lower by five orders of magnitude.