When a Ne:OCS sample was codeposited at approximately 5 K with a beam of neon atoms that were excited in a microwave discharge, the infrared spectrum of the resulting deposit included absorptions which can be assigned to OCS+, OCS-, and one or more dimer ions. Detailed isotopic substitution studies support the assignments offered for OCS+ and OCS-. The CO- and CS-stretching absorptions observed for OCS+ isolated in a neon matrix lie close to the corresponding gas-phase band centers. The CO- and CS-stretching fundamentals of OCS- isolated in solid neon were observed for the first time at 1646.4 and 718.2 cm(-1), respectively. These frequencies are in good agreement with values previously calculated using ab initio and density functional methods. The least-squares force constant fit to the data obtained in isotopic substitution experiments supports the proposed assignment. Dimer ions were also stabilized, but infrared data for these species were insufficient to provide definitive assignments.