Abstract: Mass spectra of 2. 6-DNT, 2. 4. 6-TNT, 3. 5-DNT, 3.4.5-TNT, RDX, HMS and 1.1.2.2-Digemdinitro-4-nitro-Azacyclopantane, 1.1-Gemdinitro-3. 5-Dinitro-3. 5 Azacyclohexane, 1.1-Gemdinitro-3.6-dinitro-3.6-Azacycloheptane, 1.1.5.5-Digemdinitro-3.7-Dinitro-3. 7-Azacycioactane were recorded by the electron impact. The fragmentation pathways of these compounds were studied. In 2.4-DNT and 2. 4. 6-TNT with adjacent CH_3 and NO_2 groups, important fragmentation sequences are "Ortho effect", the facile transfer of a methyl hydrogen to oxygen followed by loss of an OH group gives rise to the m/z210 ion. The similarity between the fragmentation pathways of RDX and HMX is apparent. In both compounds adduct ions are formed by addtion of NO, NO_2, nCH_2 NNO_2+H groups, producing M+NO~+, M+NO_2~+ and M+nCH_2 NNO_2+H~+ ions, n=1-5. Fragenet modes of Gemdinitro-azacyclonitroamino compounds are loss NO_2, NO and HNO_2 groups.