Crossed molecular beams experiments have been conducted to examine the chemical dynamics of the reactions of the tricarbon molecule, C-3(X-1 Sigma(+)(g)), with acetylene, C2H2(X-1 Sigma(+)(g)), ethylene, C2H4(X(1)A(g)), and benzene, C6H6(X(1)A(1g)). All reactions proceeded via a tricarbon versus atomic hydrogen exchange pathway and are defined by characteristic threshold energies of 80-90 kJ mol(-1) (acetylene), 40-50 kJ mol(-1) (ethylene), and 90-110 kJ mol(-1) (benzene) yielding the 2,4-pentadiynylidyne radical, HCCCCC(X-2 Pi) (acetylene), 1,2,3,4-pentatetraene-yl-1, HCCCCCH2((XB1)-B-2) (ethylene), and phenyltricarbon, C6H5CCC(X(2)A) (benzene) plus atomic hydrogen. Our findings suggest that tricarbon molecules can react in high temperature combustion flames with unsaturated hydrocarbon molecules to form hydrogen-deficient radicals. Published by Elsevier B.V.