Abstract We investigate the lattice and electronic thermal conductivities of uranium aluminide compounds, i.e., UAl2, UAl3 and UAl4, by density functional theory calculations. The lattice and electronic contributions to the total thermal conductivity of uranium aluminides are compared, and the contributions of phonons with different mean free times and modes to the lattice thermal conductivity of UAl3 are analyzed from the calculated cumulative and spectral thermal conductivities. The effect of Mo addition and U vacancy on the thermal conductivities of UAl3 and UAl4 is studied by considering the elastic phonon scattering due to mass difference. Both Mo addition and U vacancy are found to significantly reduce the thermal conductivities of ideal UAl3 and UAl4 even with very low concentrations. The currently predicted thermal conductivities of uranium aluminide compounds are expected to be useful to the evaluation of the effective thermal conductivity of the interaction layer formed in U-Mo/Al dispersion fuel.