The action of boron trifluoride etherate on stable aromatic nitrile oxides effected the isomerization of nitrile oxides into isocyanates competitively with their dimerization to 1,4,2,5-dioxadiazines and/or (1,2,4-oxadiazol-4-io)oxytrifluoroborates. Quenching the reaction with methanol at an earlier stage of the reaction gave methyl benzohydroximate. The reacion was interpreted in terms of the initial