A method for remote determination of oil film thickness on water surface using Iidar fluorimetric instrument has been developed. To use this method in real conditions it is necessary to determine the type of oil on the basis of remote measurement of the fluorescence spectral band shape. However, laboratory studies have shown that the fluorescence spectra of true oil differ from those of an oil film on the water surface. This difference is most significant for thin films. Therefore, a new technique is proposed to estimate true oil fluorescence spectra from the Iidar fluorescence signal of oil film on water. The feasibility of the method for monitoring oil spills on water surface was investigated in laboratory conditions using different types of oil. The operability of the proposed method was confirmed by experimental results.