This paper is a consolidated overview of what was originally presented by the co-authors at the ILSEPT 2011 conference regarding physico-chemical safety issues pertaining to ionic liquids (ILs). Indeed safety performance of ILs relating to physico-chemical hazards is very rarely investigated as it is often perceived as a non existing issue due to the lack of traditional flashpoint for these liquids. The paper outlines: (a) why it is justified to have a detailed look of physico-chemical properties of ILs in the context of separation and purification technologies, (b) sort out misleading from true general statements regarding actual safety, (c) discuss physico-chemical hazard rating systems and their limitation in the context of overall risk evaluation, and (d) report on the early findings of a joint initiative regarding the development of predictive tools for heats of combustion for ILs and experimental results obtained by use of the pyrolysis combustion flow calorimetry (PCFC) on the effective rate of heat release from ILs in fire conditions. Finally, perspectives regarding future work with regard to better knowledge and assessment of ILs physico-chemical related issues are given with the aim of serving sustainable design and use of ILs. (C) 2012 Elsevier B.V. All rights reserved.