A new high-energy organic potassium salt, 2-(dinitromethylene)-1,3-diazepentane potassium salt K(DNDZ), was synthesized by reacting of 2-(dinitromethylene)-1,3-diazepentane (DNDZ) and potassium hydroxide. The thermal behavior and non-isothermal decomposition kinetics of K(DNDZ) were studied with DSC, TG/DTG methods. The kinetic equation is $frac{d{alpha}}{dT}$ = $frac{10^{13.92}}{eta}$3(1 - $alpha$[-ln(1 - $alpha$)]$^{frac{2}{3}}$ exp(-1.52 ${ imes};10^5$ / RT). The critical temperature of thermal explosion of K(DNDZ) is $208.63;{^{circ}C}$. The specific heat capacity of K(DNDZ) was determined with a micro-DSC method, and the molar heat capacity is 224.63 J $mol^{-1};K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of K(DNDZ) obtained is 157.96 s.