The photochemical behavior of dichromated polyvinylalcohol (DCPVA) films was investigated to elucidate the first step of the reaction taking place in the photosensitive material. The work was completed for comparison by the investigation of DCPVA solutions.The difference in behavior appears in the ground state and in excited state. Processing a film modifies not only the spectral features of chromium(VI) but also the photochemical behavior. The photoredox process does not occur in basic aqueous DCPVA solution (pH=9) whereas it takes places in films prepared from that solution. The one electron photoreduction of Cr(VI) into Cr(V) is very efficient in both DCPVA films (acidic or basic) with Φ=0.65±0.05. The Φ values were calculated from the Cr(V) formation stable enough under the experimental conditions. All the results are in favor of the involvement of a complex between Cr(VI) and OH groups of polyvinylalcohol (PVA). ESR spectroscopy measurements upon irradiation further confirmed the formation and the stability of Cr(V) in PVA matrix. A very nice correlation appeared between Cr(V) behavior and the diffraction efficiency of holograms recorded in DCPVA as reported in the literature.