The photodissociation dynamics of ethynyl radical, C2H, involving seven electronic states is studied by classical trajectory calculations. Initial values of the trajectories are selected based on relative absorption intensities calculated by Mebel The energies and the derivatives are interpolated by three-dimensional cubic spline interpolator using an extended data pool. Mean square errors and standard deviations in interpolation of energies for 450 data points are found to be in the range 3.1x10(-6)-1.4x10(-5) and 1.7x10(-3)-3.8x10(-3) hartrees, respectively. The photofragments of C-2 and H are produced mainly in the X (1)Sigma(g)(+), a (3)Pi(u), b (3)Sigma(g)(-), c (3)Sigma(u)(+), A (1)Pi(u), B (1)Delta(g) electronic states of C-2 as product. The avoided crossings do not appear to be in the main dissociation pathways. The internal distributions are in good accord with the experimental results where comparison is possible, suggesting that the fragmentation mechanism of C2H2 into C-2 and H is a two step process involving C2H radical as an intermediate with a life time long enough to allow complete collection of the phase space in the experiments. (C) 2004 American Institute of Physics.