Photoinduced electron transfer reactions of ,N,N,N,’,N,’- tetramethylbenzidine (TMB) with several electron poor olefins in acetonitrile solution have been studied by using laser flash photolysis and steady-state fluorescence quenching method. The triplet state of TMB at 480nm was found to undergo reductive quenching with the electron acceptors of fumaronitrile, dimethyl fumarate, cinnamonitrile, crotononitrile and diethyl fumarate. The detection of ion radical intermediates in the photolysis reactions confirms the proposed electron transfer mechanism, as expected from thermodynamics. The quenching rate constants of triplet TMB were determined at 510nm, where all the ,k,q,T, values approach or reach to diffusion controlled limit. In addition, fluorescence quenching rate constant ,k,q,S, was also obtained by calculating with Stern-Volmer equation.