Five-dimensional quantum calculations on the thermal rate constant and the cumulative reaction probability of the H-2 + CN --> H + HCN reaction are presented. Employing a flux correlation function,these quantities are computed directly without resorting to a scattering calculation. In an analysis of the cumulative reaction probability, the contributions of the different vibrational states of the activated complex are identified and the corresponding vibrational frequencies are obtained. The calculated rate constants are compared to experiment and to results of reduced dimensionality calculations of Takayanagi, ter Horst and Schatz. (C) 1998 Elsevier Science B.V.