The first measurements of inner-valence photodetachment from a molecular negative ion are presented. Experimental and theoretical studies of CN- photodetachment around the 2-electron threshold (25-90 eV) are reported. Included are measured absolute cross sections for CN+ production by photo double detachment of CN-, and for C+ and N+ fragments produced from the dissociation of the excited molecule. The measurements also reveal the signature of inner-valence autoionization, similar to the interatomic Coulombic decay (ICD) phenomenon. This work confirms the predicted effect, which should in general be present for molecular anions, even in very small molecules. (c) 2006 Elsevier B.V. All rights reserved.