Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), as a new energetic ionic salt, is currently attracting considerable attention. The latest progress of the researches on TKX-50 is reviewed in this article, covering molecular synthesis route, crystal structure and phase transition, thermomechanical response characteristic, detonation performance, safety, compatibility and toxicity. TKX-50 possesses an applicable potential due to its advantages of ready synthesis, high energy, low mechanical sensitivity and low toxicity. However, in contrast to the conventional CHNO energetic materials, because of the different composition and inter-particle interaction of TKX-50, it possesses different thermo-mechanical properties and related origins. It is noted that the unsatisfactory thermal stability and compatibility may be an important fact constraining its application; and the thermo-mechanical response mechanism and energy release mechanism of energetic ionic salts like TKX-50 are different from those of traditional energetic materials composed of neutral CHNO molecules. All these require further insights.