Several new monocationic and unsymmetrical dicationic azide functionalized ionic liquids (ILs) were synthesized. FT-IR, H-1 NMR, C-13 NMR and elemental analyses were applied to identify the molecular structure of these compounds. The density of these ionic liquids was measured too. Unsymmetrical dicationic ionic liquids had higher density than monocationic analogues. The shear viscosity of a dicationic ionic liquid ((1-(2-azido-3-methyl-3H-imidazole-1-ium) propyl)-3-vinyl-3H-imidazole-1-ium di-dicyanamide) and its corresponding monocationic analogue were also measured. Further thermal behaviour and heat capacity of this dicationic ionic liquid were investigated by TGA and DSC techniques. TGA analysis suggested that the decomposition temperature increases with increasing the heating rate and unsymmetrical dicationic ionic liquid has good thermal stability (up to 502.4-533.6 K) and heat capacity (298-343 K). (C) 2015 Elsevier B.V. All rights reserved.