Low-temperature magnetic properties of Cd-doped Ce2 M In 8 (M=Rh and Ir) single crystals are investigated. Experiments of temperature-dependent magnetic-susceptibility, heat-capacity, and electrical-resistivity measurements revealed that Cd doping enhances the antiferromagnetic (AFM) ordering temperature from TN =2.8 K (x=0) to TN =4.8 K (x=0.21) for Ce2 RhIn8-x Cd x and induces long-range AFM ordering with TN =3.8 K (x=0.21) for Ce2 IrIn8-x Cdx. Additionally, x-ray and neutron magnetic scattering studies showed that Cd-doped samples present below TN a commensurate antiferromagnetic structure with a propagation vector ε→ = (1/2, 1/2, 0). The resolved magnetic structures for both compounds indicate that the Cd doping tends to rotate the direction of the ordered magnetic moments toward the ab plane. This result suggests that the Cd doping affects the Ce3+ ground-state single-ion anisotropy modifying the crystalline electrical field (CEF) parameters at the Ce3+ site. Indications of CEF evolution induced by Cd doping were also found in the electrical-resistivity measurements. Comparisons between our results and the general effects of Cd doping on the related compounds CeMIn 5 (M=Co, Rh, and Ir) confirms the claims that the Cd doping induced electronic tuning is the main effect favoring AFM ordering in these compounds. © 2010 The American Physical Society.