Combustion behaviours of melt-castable explosives from azetidine family, 1,3,3-trinitroazetidine (TNAZ), 3-azido-l-nitroazetidine (AZNAZ) and 3-azido-1,3-dinitroazetidine (AZDNAZ) have been studied. Burning rate measurements have been performed in a constant-pressure bomb in the pressure range of 0.1-30 MPa. A pressure interval has been found within which pressed AZNAZ samples were incapable of sustained burning. Temperature profiles in the combustion wave of TNAZ, AZDNAZ and AZNAZ were measured using thin tungsten-rhenium thermocouples. Thermocouple-aided measurements allowed the determination of the temperature dependence of TNAZ and AZDNAZ vapour pressure in a wide temperature interval, the boiling points at atmospheric pressure and the heat of evaporation. Combustion mechanisms of the energetic materials studied are discussed.