The pressure-temperature (P-T) phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7) was determined by in situ synchrotron infrared radiation spectroscopy with the resistively heated diamond anvil cell (DAC) technique. The stability of high-P-T FOX-7 polymorphs is established from ambient pressure up to 10 GPa and temperatures until decomposition. The phase diagram indicates two near isobaric phase boundaries at similar to 2 GPa (alpha -> I) and similar to 5 GPa (I -> II) that persists from 25 degrees C until the, onset of decomposition at similar to 300 degrees C. In addition, the ambient pressure, high-temperature alpha -> beta phase transition (similar to 111 degrees C) lies along a steep boundary (similar to 100 degrees C/GPa) with a alpha-beta-delta triple point at GPa and 300 degrees C. A 0.9 GPa isobaric temperature ramping measurement indicates a limited stability range for the gamma-phase between 0.5 and 0.9 GPa and 180 and 260 degrees C, terminating in a beta-gamma-delta triple point. With increasing pressure, the delta-phase exhibited a small negative dT/dP slope (up to similar to 0.2 GPa) before turning over to a positive 70 degrees C/GPa slope, at higher pressures. The decomposition boundary (similar to 55 degrees C/GPa) was identified through the emergence of spectroscopic signatures of the characteristic decomposition products as well as trapped inclusions within the solid KBr pressure media.