[Fe]-hydrogenase is a key enzyme involved in methanogenesis and facilitates reversible hydride transfer from H-2 to N-5,N-10-methenyltetrahydromethanopterin (CH-H4MPT+). In this study, a reaction system was developed to model the enzymatic function of [Fe]-hydrogenase by using N,N'-diphenylimidazolinium cation (1(+)) as a structurally related alternative to CH-H4MPT+. In connection with the enzymatic mechanism via heterolytic cleavage of H-2 at the single metal active site, several transition metal complex catalysts capable of such activation were utilized in the model system. Reduction of 1[BF4] to N,N'-diphenylimidazolidine (2) was achieved under 1 atm H-2 at ambient temperature in the presence of an equimolar amount of NEt3 as a proton acceptor. The proposed catalytic pathways involved the generation of active hydride complexes and subsequent intermolecular hydride transfer to 1(+). The reverse reaction was accomplished by treatment of 2 with HNMe2Ph+ as the proton source, where [eta(5)-C5Me5)Ir{(p-MeC6H4SO2)NCHPhCHPhNH}] was found to catalyze the formation of 1(+) and H-2 with high efficiency. These results are consistent with the fact that use of 2,6-lutidine in the forward reaction or 2,6-lutidinium in the reverse reaction resulted in incomplete conversion. By combining these reactions using the above Ir amido catalyst, the reversible hydride transfer interconverting 1(+)/H-2 and 2/H+ was performed successfully. This system demonstrated the hydride-accepting and hydride-donating modes of biologically relevant N-heterocycles coupled with proton concentration. The influence of substituents on the forward and reverse reactivities was examined for the derivatives of 1 and 2 bearing one para-substituted N-phenyl group.