The rectifying junction characteristics of the organic compound pyronine-B (PYR-B) film on a p-type Si substrate have been studied. The PYR-B has been evaporated onto the top of p-Si surface. The barrier height and ideality factor values of 0.67 +/- 0.02 eV and 2.02 +/- 0.03 for this structure have been obtained from the forward bias current-voltage (I-V) characteristics. The energy distribution of the interface states and their relaxation time have been determined from the forward bias capacitance-frequency and conductance-frequency characteristics in the energy range of ((0.42 +/- 0.02) - E-v)-((0.66 +/- 0.02) - E-v) eV. The interface state density values ranges from (4.21 +/- 0.14) x 10(13) to (3.82 +/- 0.24) x 10(13) cm(-2) eV(-1). Furthermore, the relaxation time ranges from (1.65 +/- 0.23) x 10(-5) to (8.12 +/- 0.21) x 10(-4) s and shows an exponential rise with bias from the top of the valance band towards the midgap. (c) 2006 Elsevier B.V. All rights reserved.