Reaction kinetics of ground, Ti(a3F) and V(a4F), and excited, Ti(a5F) and V(a6D), states atoms with some simple molecules have been studied by a discharge-flow tube technique. Laser-induced fluorescence (LIF) was used to determine the concentration of the metal atoms as a function of the flow rate of the reactant molecule to obtain effective bimolecular rate constants. The rate constants of reactions with OX (X = O, N, N2) and H2S show strong inverse correlation with effective ionization potentials (I.P.-Eel, where I.P. and Eel are ionization potential and electronic energy of metal atom) of the metal atoms. This result suggests that the electron transfer mechanism plays an important role in these reactions. The large rate constants for electronic excited states can be explained by the crossing between ionic and flat neutral potential energy surfaces. The inefficient reaction rates measured for ground states can be explained by the repulsive nature of 4s2 configuration which can result in a potential barrier.