General physical and chemical descriptions of phenylethylamine presented grosses-formulas, the molecular masses and indexes of chromatography maintenance of derivatives of phenylethylamine, register in the article, mescaline, and 2С-В behave to that. During expert research of substances of a group of derivatives of phenylethylamine, the task of quality authentication of research objects that have an alike molecular structure stands before experts. The analytical approach intended for authentication of the investigated substances envisages the use of a few unconnected inter se methods: methods of providing of high level of selectivity, middle and subzero level of selectivity. The brought analytical charts over, that give a scientifically reasonable result, when after every method positive result that confirms each other are arrived at. The aim of the research of this work is an analysis and approbation of existent methodologies of authentication of substances that have an alike molecular structure, and their quantitative research. The process of quality authentication of mescaline and 2С-В, or other derivatives of phenylethylamine, includes for itself extraction and preparation of the test. During realization of screening of the investigated psychotropic substances (mescaline, 2С-В) used: method of quality analytical reactions, method of TLC, method of ultraviolet spectroscopy, method of infra-red spectroscopy, method of gas mass-spectrometry. Quantitative determination of mescaline and 2С-В was conducted by the method of gas mass-spectrometry. At the research of substances of a group of derivatives to the phenylethylamine expert, it follows to follow the presence of corresponding literary sources and the presence of corresponding analytical equipment (GC, GC/MS, LC/MS, and others like that). In accordance with it, it’s needed to use those or other methodologies of research of substances. The indicated methodologies are subject to obligatory verification before application in a laboratory. Key words: phenylethylamine, mescaline, 2C-B, chromatography, spectrophotometry, chromato-mass spectroscopy.