Electrical resistivity measurements have been carried out between 20 and 300 K on Ce2Fe16.8, on the Ce2Fe17−xAlx solid solutions, with x = 0.4, 1, 2, 5, 6, 8, and 9, and on the Ce2Fe17−xSix solid solutions, with x = 0.2, 0.4, 1, and 2, with the four probe method. The temperature dependence of the resistivity of Ce2Fe16.8 shows an inflection at 110 K, a feature which is also observed in the temperature dependence of the magnetization and is related to a magnetic phase transition from a helical structure, above 110 K, to a fan structure, below 110 K. The temperature dependence of the resistivity of Ce2Fe16.8 is characteristic over the investigated temperature range of weak antiferromagnetic behavior with incommensurate periodicity as has been observed in the earlier neutron diffraction study. The resistivity of Ce2Fe17−xAlx increases with temperature in agreement with a density of states at the Fermi level dominated by the d band. For a given temperature, the resistivity increases substantially and regularly with x for both series of solid solutions because of an increase in the number of conduction electron scattering potentials. This increase in resistivity also corresponds to a decrease in the number of conduction electrons due to their increasing transfer into the localized cerium 4f orbitals as the cerium valence state changes from a mixture of trivalent and tetravalent in Ce2Fe17 to predominantly trivalent in Ce2Fe17−xAlx and Ce2Fe17−xSix with increasing x. © 1997 American Institute of Physics.