This work examines the possibility of real-time detecting of single nitro compounds microcrystals [cyclotrimethylenetrinitramine (RDX) and pentaerythritol tetranitrate (PETN)] with sizes of ∼130 to 600 μm by the terahertz (THz) imaging. A THz video camera based on a microbolometer matrix was used to record images in transmission and reflection optical schemes. A photoconductive antenna was used as a THz source. It was experimentally demonstrated that the spectral selectivity of identifying of nitro compounds microcrystals in the THz range strongly depends on their size, and the results of mathematical modeling based on the Mie scattering theory showed that this effect is due to the complex dependence of the extinction cross section of the microcrystals on their size. The results of the work can be used in the development of real-time THz visualization systems.