Abstract The assignment of configurations to isomers of 2-halo-2-phenylvinylboranes and 1- halo-1-phenyl-2-deuteroethylenes described in a previous paper has been revised. The mechanism of haloboration of n-hexyne-1 is discussed in the light of the geometrical isomer ratios of 2-halohex-1-ene-1-ylboranes obtained as products.