A nitrate-based ionic liquid compound, TMEDA.8HNO3, was synthesized from hypergolic bipropellants N,N,N',N'-tetramethylethylenediamine (TMEDA) and nitric acid by premixing them carefully at a stoichiometric molar ratio of 1:8. The overall ignition and combustion behaviors of this liquid propellant were examined by using a high-pressure strand burner with optical access, coupled with a high-speed video camera for capturing and analyzing the liquid- and gas-phase processes as well as measuring the regression rates of the liquid strands. TMEDA.8HNO3 has a pressure deflagration limit (PDL) of approximately 300 psi, below which the liquid strand regresses without a luminous flame. Burn rates of this liquid propellant were measured from 400 to 1000 psi. Thermal decomposition of TMEDA.8HNO3 was investigated by a confined rapid thermolysis setup with heating rates on the order of 2,000 K/s coupled to rapid-scan Fourier transform infrared (FTIR) spectroscopy of the evolved gases. Over the temperature range from 50 to 80°C, the major IR-active gaseous species evolved from the condensed-phase decomposition are HNO3, NO2, H2O, CO2, HCOOH, and glyoxylic acid (HOCCOOH). At higher temperatures, additional species such as CH2O, (CH3)2NNO, NO and N2O also evolved. Possible decomposition pathways of TMEDA.8HNO3 are discussed based on the rapid thermolysis studies.