Highly correlated ab initio methods are used to predict the equilibrium structures and spectroscopic parameters of the SiC3H− anion. The total energies and physical properties are reported using CASSCF/MRCI, RCCSD(T), and RCCSD(T)-F12 approaches and extended basis sets. The search of stable geometries leads to a total of 12 isomers (4 linear and 8 cyclic), for which electronic ground states have close-shell configurations. The stability of the linear form, l-SiC3H−, is prominent. For the most stable linear isomer, the Be equilibrium rotational constant has been calculated with RCCSD(T) and a complete basis set. Core-correlation and vibrational effects have been taken into account to predict a B0 of 2621.68 MHz for l-SiC3H− and 2460.48 MHz for l-SiC3D−. The dipole moment of l-SiC3H− was found to be 2.9707 D with CASSCF/aug-cc-pV5Z and the electron affinity to be 2.7 eV with RCCSD(T)-F12A/aug-cc-pVTZ. Anharmonic spectroscopic parameters are derived from a quadratic, cubic, and quartic RCCSD(T)-F12A force field and second order perturbation theory. CASSCF/MRCI vertical excitations supply three metastable electronic states, Σ1+ Σ3+ and Δ3. Electron affinities calculated for a series of chains type SiCnH and SiCn (n=1–5) allow us to discuss the anion formation probabilities.