Two-body Coulomb explosion of allene induced by an ultrashort (similar to 40 fs) intense laser field is investigated by the coincidence momentum imaging (CMI) method. From the CMI maps, two types of two-body Coulomb explosion pathways, C3H42+ -> CHm+ + C2H4-m+ (m = 1-3) and C3H42+ -> C3H4-n+ + H-n(+) (n = 1-3), are securely identified. The formation of CH3+, C2H3+, and H-3(+) shows that the chemical bond rearrangement associated with the ultrafast hydrogen migration occurs prior to the ionization into C3H42+ and that the extent of the hydrogen migration determines either one of the two initially identical C=C chemical bonds is broken. (C) 2009 Elsevier B. V. All rights reserved.