Electron energy-loss spectroscopy in the near ionized edge region (electron energy-loss near-edge structure, ELNES) is a useful tool for the investigation of the electronic structure of the unoccupied state. Electron energy-loss spectroscopy in the high energy-loss region at large momentum transfer-electron Compton scattering from solids (ECOSS)-is a unique technique to determine the momentum distribution of the electronic ground state in a material. Therefore, the investigation of both the occupied and unoccupied states in a material can be done in one experiment. This thesis covers experimental and theoretical investigation of electron energy-loss spectroscopy, emphasizing the combination of those two aspects. The use of electron Compton scattering instead of photon Compton scattering to determine electron momentum distributions in atoms and molecules can be traced back to 1938. At that time, electron Compton scattering experiments were carried out on gases. In 1981, B.G. Williams et al showed that electron Compton scattering from solids can be carried out in the transmission electron microscope by means of measuring electron energy-loss spectra at large scattering angle in the diffraction mode. The most severe problems of the technique were multiple scattering, strong contributions from Bragg scattering and the low signal in the Compton scattering region. The instrumental improvements in energy and spatial resolution, statistical accuracy, and reproducibility of recent years make it is possible to carry out experiments which could hardly work a decade ago. On modern electron microscopes, one can get an electron Compton profile in tens of seconds which is much shorter than several hundred seconds required 20 years ago. Also the methods of background subtraction have improved. These motivate a revival of the ECOSS technique. The benefits of recording Compton profiles in a very short time are obvious. It opens up new possibilities: systematic studies of technological interesting materials become possible. The recording time is usually minutes, not hours or days, making a study of momentum transfer, orientation, composition and temperature dependence of Compton profiles feasible. The resolution and statistical accuracy have been improved simultaneously. In this thesis, electron energy-loss near edge structures (ELNES) and electron Compton scattering from solids (ECOSS) of silicon (cubic crystal), natural graphite (hexagonal crystal) and amorphous carbon film (structureless) are systematically studied in the transmission electron microscope (TEM) by means of recording electron energy-loss spectra (EELS) at different scattering angles. The momentum transfer dependence of ECOSS for silicon and graphite was studied in the range from 6.0 to 9.0 a.u.. The valence Compton profile was obtained after a theoretical core profile subtraction was performed based on the Hartree-Slater model. The electron Compton profiles coincide well with other conventional Compton profile measurements, as well as with theory, thus establishing the validity of the technique. Electron Compton profiles of graphite have been recorded from the crystal with the c axis parallel and at 30-to the beam direction. A significant anisotropy has been found, which agrees fairly well with previous measurements on graphite. The angular and energy dependences of the and structures of ELNES of graphite were completely separated, the results were also in fair agreement with theory.