Equations are established for the pressure increase as a function of time for the self-decomposition of terrafluoroethylene (TFE) for both a uniform tube and a sphere. The resting gas is locally ignited at one end of the tube and in the center of the sphere respectively. Buoyancy is ignored. Due to the low kappa-value, major simplifications are justifiably introduced. Apart from the geometrical factors, the pressure increase as a function of time is solely controlled by the pressure increase ratio, Pi, and the intrinsic flame speed, v(o), thus the equations also are applicable to other gaseous TFE-mixtures of technical interest. The average flame speed is 0.1-0.3 m/s, which compares well with other explosive gaseous mixtures, and v(o) lies in the range of the molecular diffusion rate. The self-decomposition of TFE does not seem to exhibit any specific patterns.