Two cobalt compounds, Cp*Co(CO)I₂ (1) and CpCo(CO)I₂ (2) (Cp* = η⁵-C₅Me₅, Cp = η⁵-C₅H₅), catalyze the dehydrogenation of ammonia borane under either anaerobic or aerobic conditions and are also effective hydrogenation catalysts for alkenes and alkynes using ammonia borane as a hydrogen source, also in the presence of air.