Nitromethane anion and nitromethane dimer, trimer, and hydrated cluster anions were studied by photoelectron spectroscopy. Vertical detachment energies, estimated electron affinities, and solvation energies were obtained from the photoelectron spectra. Cluster structures were investigated using theoretical calculations. Predicted detachment energies agreed with experiment. Calculations show water binds to nitromethane anion through two hydrogen bonds. The dimer has a non-linear structure with a single ionic C-H center dot center dot center dot O hydrogen bond. The trimer has two different solvent interactions, but both involve the weak C-H center dot center dot center dot O hydrogen bond. (C) 2016 Elsevier B.V. All rights reserved.