The 364 nm photoelectron spectrum of Si2C3- is reported, together with high level ab initio calculations of the linear anion, and six linear and eight nonlinear structures of the neutral Si2C3. The adiabatic electron affinity of Si2C3, corresponding to the transition from the linear anion to the lowest electronic state of the linear singlet neutral, is found to be 1.766+/-0.012 eV. Theoretical results were essential for interpreting the spectrum. The level of theory necessary to accurately describe the electronic structure of Si2C3 cluster isomers is presented and discussed. Several vibration frequencies for the neutral linear structure are obtained from the spectra and compared to results from different levels of theory.