The insertion of alcohols into carbodiimides mediated by benzimidazolin-2-iminato actinide complexes [(Bim(R1/R2)N)AnN"3] [N" = N(SiMe3)(2)] is presented herein. Analysis of single-crystal data revealed that steric hindrance, rather than electronic properties, plays an important role in determining the accessibility for this insertion process. All actinide complexes showed excellent activities under very mild conditions. Stoichiometric reactions in combination with kinetic and thermodynamic studies allow us to propose a plausible active species and a mechanism for the catalytic cycle.