The paper proposes a simple and affordable way to identify and authenticate butter by a colorimetric method using a smartphone and chemometric analysis. Identification and authentication of dairy products was carried out by an analytical signal in the RGB colorimetric system when registering the intrinsic fluorescence of samples due to exposure to monochromatic ultraviolet light (365 nm). A test device based on a smartphone and a method for measuring colorimetric parameters in an additive RGB system for identifying and authenticating declared products of dairy origin are proposed. When studying colorimetric characteristics, iPhone X and iPhone XIII smartphones (Apple, USA) equipped with specialized RGBer software were used as a color recording device. The processing of the data array (for three variables R, G, and B) was carried out using the XLSTAT software product. The method of principal components and hierarchical cluster analysis were used to separate the samples by species (source of raw materials). Approbation of the presented approach was carried out on samples of commercially produced butter (32 samples) purchased in retail stores. The use of chemometric analysis methods made it possible to confirm the authenticity of the butter and reveal the facts of falsification. The results obtained correlated with the data of the arbitration method of gas-liquid chromatography in assessing the fatty acid composition of the fatty phase of the product. The proposed approach and its technical solution are characterized by the availability of component materials and digital equipment used in the operation of the test device. In addition, the mobility of the system and the ease of recording the colorimetric characteristics of the fluorescence of the analyzed object, combined with the clarity of the presented final information obtained using chemometric algorithms, makes this direction promising in monitoring laboratory and personal studies. For citation: Amelin V.G., Shogah Z.А.C., Bol’shakov D.S., Tretyakov A.V. Detection of falsification of butter by colorimetric method using smartphone and chemometric analysis. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 53-61. DOI: 10.6060/ivkkt.20236602.6717.