Abstract The structures, electron affinities, dissociation energies, hardness, and dipole moments of YbSi n ( n = 4–10) and their anions were examined using B3LYP, TPSSh, PBE and wB97X methods. The lowest-energy structures can be regarded as replacing a Si of the ground-state structure of Si n +1 with a Yb atom. The theoretical adiabatic electron affinities (AEAs) of YbSi n are in excellent agreement with experimental data. The average absolute errors from experiment are by 0.08, 0.07, 0.05 and 0.08 eV at the B3LYP, the TPSSh, the PBE and the wB97X levels, respectively. Theoretical AEAs of 2.33 ± 0.05 eV for YbSi 9 are more reliable than the experimental value of 2.60 ± 0.05 eV. The hardness analysis reveals that doping Yb atom to Si n ( n = 4–10) clusters raises the photochemical sensitivity. The dissociation energies of Yb atom from YbSi n and their anions were calculated to examine relative stabilities.