We report on the light induced spin crossover dynamics of [Fe(phen)(3)] (BF4)(2) (phen = 1,10-phenantroline) complex dissolved in acetonitrile. This complex was excited by picosecond and femtosecond laser pulses whose central frequency was centered on the (1)A(1) -> (MLCT)-M-1 optical transition. Our analysis that well reproduces the recorded transient absorptions suggests this complex relaxes following inter-system crossing cascade: (MLCT)-M-1(S = 0) -> (MLCT)-M-3(S = 1) -> T-5(2)(S = 2) -> (1)A(1)(S = 0). The (MLCT)-M-3 and T-5(2) states were identified, thanks to the triplet-triplet (MLCT)-M-3 -> (MLCT)-M-3* and T-5(2) -> (MLCT)-M-5 optical transitions. Our experiments well agree with the relaxation mechanism recently proposed and clearly indicate the impact of the solvent on the measured relaxation constant time. (C) 2011 Elsevier B. V. All rights reserved.