Adiabatic and diabatic potential-energy surfaces (PES's) for the interaction of Ne(S-1(0)) with the CN molecule in its ground (X (2) Sigma(+)) and first excited (A (2) Pi) electronic states were determined using multireference configuration-interaction calculations. The three electronically adiabatic potential-energy surfaces (PES's, 2 A' and 1 A '') are transformed to three diabatic PES's plus one additional PES which describes the coupling between the two diabatic PES's of A' symmetry which correlate asymptotically with the X (2) Sigma(+) and A (2) Pi states of CN. These four diabatic PES's are then used in the study of the predissociation of the CN(A 2 Pi)Ne complex, subsequent to electronic excitation of the ground-state complex [CN(X)Ne]. Two channels: Fast spin-orbit predissociation [CN(A (2) Pi(1/2), upsilon = 3)Ne --> CN(A (2) Pi(3/2), upsilon = 3) + Ne] and slow electronic predissociation [CN(A (2) Pi(3/2), upsilon = 3)Ne --> CN(X (2) Sigma(+), upsilon = 7) + Ne] are investigated. The quantum flux method was used to determine the positions and widths of the metastable levels of the complex. For these predissociation processes, comparison is made with the experimental investigation by Fei, Lawrence, Chen, and Heaven. (C) 1997 American Institute of Physics.