Our recent progress in developing Ir complex-catalyzed N-alkylation systems employing alcohols as alkylating reagents is described. These catalytic systems involving hydrogen transfer process is environmentally benign because it produces water as the sole byproduct. These results demonstrate the high potential of Ir complexes for catalyzing the dehydrative N-alkylation reaction of amine and ammonia derivatives with alcohols as alkylating reagents, which will contribute to realizing sustainable chemistry.