[en] Temperature-dependent line width and line shift measurements between 7 and 280 K have been performed for a number of absorption transitions in the 4000-21,000 cm^-1 energy range of the U³⁺:LaCl₃, Nd³⁺:LaCl₃ and U³⁺:LaBr₃ single crystal spectra. The values of the electron-phonon coupling parameter α-bar were determined for U³⁺:LaCl₃ and Nd³⁺:LaCl₃ by a fit of experimentally observed line widths to an equation containing the temperature dependent broadening due to the Raman two-phonon process. For both ions diluted in LaCl₃ the values of the α-bar parameters are considerably lower than in K₂LaCl₅, and the value of α-bar for U³⁺ in the LaCl₃ host is markedly larger as compared with that of Nd³⁺. Factors influencing these differences are discussed. With a temperature increase a blue shift of the absorption lines of the U³⁺ ions in LaCl₃ and LaBr₃ is observed. A comparison has been performed among the electron-phonon coupling parameters obtained from an analysis of the line widths of the U³⁺:LaCl₃ single crystal and those determined from temperature induced line shifts as well as between the magnitudes of the absolute increase in line width and line shifts in the 7-290 K temperature range for U³⁺ doped LaCl₃ and LaBr₃ crystals. The electron-phonon coupling is stronger for U³⁺ in the tribromide as compared with the trichloride host which is mainly due to a larger covalency of the first one