Relative values of thermospheric photoelectron energy distributions between 2 and 100 eV were measured over the altitude range 100--220 km by using a 127¿ cylindrical electrostatic deflection analyzer flown on a rocket. The measured photoelectron spectra display distinct features that are theoretically predicted (Victor et al., 1976; Jasperse, 1977) and are similar to those obtained in recent satellite experiments (Doering et al., 1975, 1976). The valleylike structure in the energy range 2--5 eV attributed to resonant-vibrational excitation of N2 was observed in more detail and over a greater altitude range than that measured previously. The prominence of this low-energy valley decreases with increasing altitude above about 150 km and disappears above 200 km, in general agreement with theory. However, in contrast to theoretical predictions, the low-energy valley also appears to become less prominent as altitude decreases below about 140 km, down to the lowest observations at 100 km.