The following ion–molecule reactions involving fragment ions in vinyl chloride have been studied and rate constants measured for ions of 2.4 eV exit energy.[Formula: see text]The reaction of the C2H3Cl+ molecule-ion produces C3H4Cl+, C4H5Cl+, and C4H6Cl+ both in a second order and a third order reaction. The apparent rate coefficient for the second order reaction is approximately 1 × 10−11 cm3 molecule−1 s−1 while that for the third order reaction is approximately 1 × 10−25 cm6 molecule−2 s−1. The product distributions from both the second and third order reactions have been determined.In vinyl bromide the C2H3+ ion produces C4H5+, C4H6+, and C2H4Br+ while the C2H3Br+ ion reacts to form C4H6Br+ both in a second order and a third order reaction.