We　report　the　formation　of　H2+　and　C2+　from　dissociation　of　acetylene　induced　by　α-particle　irradiation.　The　unusual　dissociation　channel　[C2H2]2+　→　H2+　+　C2+　is　unambiguously　identified　by　measuring　the　time-of-flight　of　both　fragmented　ions　in　coincidence.　Our　quantum　chemical　calculation　confirms　the　existence　of　this　dissociation　pathway.　It　shows　that　[HCCH]2+　is　firstly　populated　to　the　3Π　excited　electronic　state,　followed　by　acetylene-vinylidene　isomerization,　and　finally　the　vinylidene-like　intermediate　dissociates　to　H2+　and　C2+.　This　dissociation　channel　is　the　simplest　prototypical　reaction　involving　H　migration,　H-H　combination,　and　C-H　bond　cleavage.　The　current　study　plays　an　important　role　for　understanding　the　H2+/H3+　formation　reactions　from　organic　di-cations　in　an　interstellar　medium.