Organic azides are unstable chemical compounds, which can be easily decomposed or exploded. This work introduces three novel correlations for the prediction of melting point of different types of organic azides containing alkyl azides, alkenyl azides, aryl azides, acyl azides and heteroazide compounds. These models are based on the elemental composition as additive parameter and the contribution of some specific polar groups/structural moieties as non-additive functions. The new correlations have been used for 259 different organic azide compounds including complex molecular structures. The new models were validated by internal and external validation tests where their applicability domains were defined and analyzed. Third correlation, in which the contribution of Specific Polar Groups (SPG) and Inefficient Packing Factor (IPF) beside the number of carbon, hydrogen and nitrogen atoms and the number of azide groups are considered, gives the best predictions. It shows good performances in robustness and predictive power through different validation techniques. It also provides good statistical results and more reliable predictions as compared with two complex methods of the best available computer codes. (C) 2016 Elsevier B.V. All rights reserved.