In this paper the transformation of the amorphous film obtained by vacuum evaporation at room temperature of 3-ethyl-2-(3-ethyl-2-benzothiazolinylidene) ethyliden] rhodanine onto SnO₂ oonducting glass substrate to polycrystalline film has been studied.During the transformation, the photocondnctivity of the film increases with the growing of the microcrystals and finally reaches a steady value. Results of the photoconductivities measured by DC and AC methods have also been reported.Monocrystals of the merocyanine dye have been grown from the solution in the presence of a polymer.From the results of X-ray analysis of the monocrystal it has been shown that the planar molecules in the crystal are stacked along a-axis.The crystal structure is helpful in explaining the mechanism of photoconduction of the film.