Rotational states of dipole-bound anions of HCN are studied both experimentally and theoretically. The ground state experimental electron affinity (ea), 1.56 meV, is in good agreement with present and one earlier theoretical value. The predicted binding energy for the J = 1 state, 1.2 meV, is observed, whereas J = 2 is too fragile for observation and J = 3 is unbound. (c) 2009 Elsevier B.V. All rights reserved.