Semicarbazide hydrochloride reacted with aq. 85% HCOOH at 85-90 degrees C to give TO which, with excess acid distd. off and reaction mixt. neutralized with aq.10% Na2CO3, was nitrated to yield NTO m. 267-9 degrees C. This was recrystd. in 12.5 wt. parts of (9:1 v/v) EtOH-H2O, 2 hrs., 1000 rpm, at cooling rates of (i) 20 (ii) 3, and (iii) 10 degrees C/min, to yield (i) spherical 50-150 mu m polycrystals, bulk d. 0.77, and tap bulk d. 0.96; (ii) 50-350, 0.92, and 1.05; (iii) 50-300 mu m, 0.81, and 1.01 g/cm(3), resp. NTO m.p., 267-8 degrees C. Plastic-bonded explosives (PBX) were prepd., contg. 84 or 90% of 10-150-mu m hexogen and NTO as additive, in a butadiene-styrene rubber as binder plastified with 16 or 10% of dioctyl adipate and oil. When added in 20, 20-60, and 80% to either the 84% or the 90% PBX, the NTO additive reduced, leveled off, and still more reduced the sensitivity of the PBX to impact, resp. The EtOH-H2O was superior to ethylene glycol as solvent The properties of 3-nitro-1,2,4-tilazol-5-one and investigations of this material in order to obtain suitable crystalline form were presented. The tests of bulk density and tap bulk density of obtained crystals were carried out. The grain size characteristic and grain morphology were investigated. The resulting crystals were used to prep. of Plastic Bonded Explosives. The tests of the PBX sensitivity to mechanical impacts were made.