The authorship assessment of art works represents one of the most complex and delicate problems, particularly for the art works created during the second half of the XIXth century and the begining of the XXth century, when the falsification industry had unprecedented proportions. In this context, the determination of the authorship of art works should start with the technical and stylistical analysis and has to be completed by physico-chemical analysis in order to answer on a scientific basis to various aspects related to the technique used by the artist, composition of pigments, or the impact caused by environmental and incidental factors on the degradation state of art issues. This article aims at demonstrating the authorship of two paintings attributed to Victor Brauner, considered at present one of the greatest artists of the XXth century. In order to assure a scientific approach of these art works and for a better understanding of the correlation between the chromatics of paintings and the composition of pictorial materials, a data base has been created, consisting in a number of 29 pigments covering the main groups of monochromatic colors, which individual or in a mixture can lead to the wide palette of nuances used in paintings. This collection has been completed by other 4 pigments dated in 1920 period when these drawings have been created. The techniques used for physico-chemical analysis of standard pigments and of the samples taken from the works were: UV-VIS-NIR spectroscopy in diffuse reflectance mode, FT-IR spectroscopy, elemental analysis and chromatic analysis in CIE - L*a*b* system. By corroborating spectral and chromatic analysis of samples with elemental analysis of metals in the signature, the authorship of two of Victor Brauner paintings has been certified.