The application of hexanuclear halide clusters as catalysts was made. Molecular halide clusters of Nb, Mo, Ta, and W possessing an octahedral metal core were treated in a helium stream at 250 degreesC for 1 h before introduction of phenyl acetate. These clusters served as catalysts for decomposition of the ester to phenol and ketene. Raman and X-ray analyses showed that the development of the catalytic activity was attributable to the partial loss of the inner halogen ligands.