The structures and properties of metal cationized complexes of 9-ethylguanine (9eG) and 1-methylcytosine (1mC), (9eG:1mC)M+, where M+ = Li+, Na+, K+, Rb+, Cs+ as well as the protonated complex, (9eG:1mC)H+, have been studied using a combination of IRMPD spectroscopy and computational methods.