Method for identifying a material (M) by spectral analysis of electromagnetic radiation able to pass through this material, comprising the following steps: - measuring a spectrum of electromagnetic radiation emitted through the material to be identified (M), - determining at least one energy band (Bm), referred to as a measurement band, and spectral coefficients of a comparison function in this measurement band, using the measured spectrum, - estimating (PH1, PH2; 306, 308, 310, 312), using the determined spectral coefficients, the nature and/or the thickness of the material to be identified (M) on the basis of a set of reference spectral parameters relating to reference materials and/or thicknesses, these reference spectral parameters being defined for each reference material and/or thickness in at least one energy band referred to as a reference band specific to each reference material and/or thickness, characterized in that the estimation comprises at least the two following steps: - prior selecting (208 1 , ..., 208 p ; 308) of a plurality of reference materials and/or thicknesses, referred to as possible candidates, from a comparison of the spectral coefficients determined with at least one portion of the reference spectral parameters in a first common energy band that corresponds to the intersection of at least one portion of the reference bands and the measurement band, - determining (210 1 , ..., 210 p ; 310) at least one new common energy band that corresponds to the intersection of the reference bands of at least one portion of the possible candidates and the measurement band, - estimating (222; 312) the nature and/or the thickness of the material to be identified (M) from a comparison of the spectral coefficients determined with the spectral parameters of said at least one portion of the possible candidates, in said new common energy band. - measuring a spectrum of electromagnetic radiation emitted through the material to be identified (M), - determining at least one energy band (Bm), referred to as a measurement band, and spectral coefficients of a comparison function in this measurement band, using the measured spectrum, - estimating (PH1, PH2; 306, 308, 310, 312), using the determined spectral coefficients, the nature and/or the thickness of the material to be identified (M) on the basis of a set of reference spectral parameters relating to reference materials and/or thicknesses, these reference spectral parameters being defined for each reference material and/or thickness in at least one energy band referred to as a reference band specific to each reference material and/or thickness, - prior selecting (208 1 , ..., 208 p ; 308) of a plurality of reference materials and/or thicknesses, referred to as possible candidates, from a comparison of the spectral coefficients determined with at least one portion of the reference spectral parameters in a first common energy band that corresponds to the intersection of at least one portion of the reference bands and the measurement band, - determining (210 1 , ..., 210 p ; 310) at least one new common energy band that corresponds to the intersection of the reference bands of at least one portion of the possible candidates and the measurement band, - estimating (222; 312) the nature and/or the thickness of the material to be identified (M) from a comparison of the spectral coefficients determined with the spectral parameters of said at least one portion of the possible candidates, in said new common energy band. <EOS>