Infrared Raman scattering studies were made on a composite of poly(ethylene oxide) (PEO) polymer + (NH4)(4)H-2(SeO4)(3) crystal. Comparison of the spectra obtained for the composite of PEO + (NH4)(4)H-2(SeO4)(3) and the mixture of dry powders of the same contents suggests the existence of a complex in the composite. The degree of crystallinity of the polymer increases with growing content of (NH4)(4)H-2(SeO4)(3) in the composite.