Electrical resistivity measurements have been carried out between 20 and 300 K onCe2Fe16.8, on theCe2Fe17−xAlxsolid solutions, withx=0.4, 1, 2, 5, 6, 8, and 9, and on theCe2Fe17−xSixsolid solutions, withx=0.2, 0.4, 1, and 2, with the four probe method. The temperature dependence of the resistivity ofCe2Fe16.8shows 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 ofCe2Fe16.8is 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 ofCe2Fe17−xAlxincreases with temperature in agreement with a density of states at the Fermi level dominated by thedband. For a given temperature, the resistivity increases substantially and regularly withxfor 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 cerium4forbitals as the cerium valence state changes from a mixture of trivalent and tetravalent inCe2Fe17to predominantly trivalent inCe2Fe17−xAlxandCe2Fe17−xSixwith increasingx. ©1997 American Institute of Physics.