The observation of spin state relaxation of iron (III) spin crossover complexes in solution [1] (as result of photo perturbation 2T  6A spin equilibrium) stimulated the discovery LIEEST effect [2]. In our work, the photoinduced spin - polarized transient electron paramagnetic resonance (EPR) spectra of high spin (S=5/2) and low spin (S=1/2) state under 6A  2T transition [Fe(salten)X]BPh4 (X=Him, Pic) have been observed in powder samples. The complexes Fe(III) in [Fe(salten)Him]BPh4 are high-spin in T=(5-300)K as shown by investigations of continuous-wave EPR. Incomplete spin transition from the high-spin state to the low-spin state takes place in compound with X= Pic in the interval (280-70) K. The results of time-resolved X-band EPR study of [Fe(salten)Him]BPh4 are shown in Figure: a) time-resolved spectrum at t = 3100 ns after the laser pulse; b) time-profile of EPR signals at H = 160mT and T = 5K; c) time-profile of EPR signals at H=340mT and T=60K. Our data show an emissive signal formed after the laser flash ( = 532 nm), which coincides in form with the integral continuous-wave EPR spectrum of high-spin state (160  10 mT). We attribute this signal to the enhanced polarization of the ground state with S = 5/2. The additional absorption signal arises at temperature of 60K in magnetic field corresponding to the position of signal from the low-spin state (340  20 mT). The time profiles of the emissive EPR signals is characterized by two exponential functions describing the fast and slow kinetics. The kinetic parameters of decay curves for EPR signals at different temperature are defined. The time profiles of the absorption EPR signal is characterized by one exponential function with the rate constant 1.5·105 s -1. The similar results were obtained for spincrossover compound [Fe(salten)Pic]BPh4 with lowspin ground state (S = 1/2) at T < 70K. Our investigations have shown that the time-resolved EPRspectroscopy allows to study spin-state relaxation dynamic (intersystem crossing) in powder of low- and high-spin Fe(III) systems (not only in solution).