New cumulenic ions, SNCCO+, SCNCO+, SNCCS+, and SCNCS+, have been generated by dissociative ionization and characterized by tandem mass spectrometry techniques. The stabilities of the corresponding radicals were evaluated by neutralization-reionization (NR) experiments and supported by ab initio molecular orbital calculations at the G2(MP2,SVP) level. The neutral radicals, SNCCS., SCNCS., and SNCCO., are found by experiment and theory to be observable species in the gas phase, while SCNCO. is not accessible under NR conditions. All the cations are potential energy minima, and their calculated fragmentation energies are in reasonable accord with experiment.