Charged transient species in the oxygen system have been trapped in solid argon and neon using electron impact, Townsend discharge, and laser-ablation methods. The previously identified O-3(-), O-4(-), and O-4(+) species are observed in these experiments. Absorptions at 1435.0 and 1429.5 cm(-1) in solid neon are characterized as cyclic-O-6(+) and trans-O-6(+), respectively, on the basis of annealing behavior, isotopic substitution, multiplet structure in mixed O-16(2) + O-18(2) experiments, and density functional calculations. Cyclic-O-6(+) is observed at 1416.1 cm(-1) in solid argon, a smaller displacement than found for cyclic-O-4(+) in solid argon.