For the first time, the optical parameters of mats of polymeric, polyacrylonitrite (PAN) nanofibers containing ferroelectric and semiconducting antimony selenoiodide (SbSeI) are presented. The novel material has been made by electrospinning. The SbSeI nanowires, used as the filler, have been prepared sonochemically using elemental Sb, Se and I-2 in the presence of ethanol under ultrasonic irradiation (20 kHz, 565 W/cm(2)) at 323 K within 2 h. The products have been characterized by using techniques, such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, high-resolution transmission electron microscopy and selected area electron diffraction. The spectral characteristics of diffusive transmission and reflectance of PAN/SbSeI mats have been measured at room temperature to determine absorption and scattering coefficients. The absorption spectrum of PAN/SbSeI has been least square fitted with the theoretical dependence appropriate for the sum of the indirect allowed absorption with an absorption/emission of phonons without excitons and a constant absorption term. The indirect allowed optical energy gap of PAN/SbSeI has the value E-gia = 1.59 (1) eV.