The temperature characteristics of electron beams and trapped particles of large pitch angles during substorms have been studied by examining the plasma data of the University of California at San Diego experiment on board the geostationary ATS 6 satellite. Approximating the observed distribution functions by a single Maxwellian or a superposition of two Maxwellians, we have deduced that the electron distribution function is characterized by two temperatures, ≲1 and ~3 keV. The 3-keV component is observed at all pitch angles from ~10¿ to 90¿. The ≲1-keV component initially appears only within the electron beams which are confined to small pitch angles (≲30¿). With time, this low-temperature component appears at larger pitch angles (>30¿). This observation has been interpreted in terms of scattering of the electron beams to large pitch angles.