Near-equilibrium potential energy surfaces have been calculated for both the PCS radical and its anionusing a composite coupled cluster approach based on explicitly correlated F12 methods in order toprovide accurate structures and spectroscopic properties. These transient species are still unknownand the present study provides theoretical predictions of the radical and its anion for the first time.Since these species are strongly suggested to play an important role as intermediates in the interstellarmedium, the rotational and vibrational spectroscopic parameters are presented to help aid in theidentification and assignment of these spectra. The rotational constants produced will aid in groundbasedobservation. Both the PCS radical and the PCS– anion are linear. In the PCS– anion, which hasa predicted adiabatic electron binding energy (adiabatic electron affinity of PCS) of 65.6 kcal/mol,the P–C bond is stronger than the corresponding neutral radical showing almost triple bond character,while the C–S bond is weaker, showing almost single bond character in the anion. The PCS anionshows a smaller rotational constant than that of the neutral. The !3 stretching vibrational frequenciesof PCS are red-shifted from the radical, while the !1 and !2 vibrations are blue-shifted with !1demonstrating the largest blue shift. The ro-vibronic spectrum of the PCS radical has been accuratelycalculated in variational nuclear motion calculations including both Renner-Teller (RT) and spinorbit(SO) coupling effects using the composite potential energy near-equilibrium potential energyand coupled cluster dipole moment surfaces. The spectrum is predicted to be very complicated even atlowenergies due to the presence of a strong Fermi resonance between the bending mode and symmetricstretch, but also due to similar values of the bending frequency, RT, and SO splittings.