The structure of a sulfur-yellow pigment from the lichen Melanelixia subaurifera, historically referred to as subauriferin, has been determined. Chromatographic analysis of lichen extracts revealed that this compound coincides with secalonic acid A, a known yellow pigment found in both lichenized and non-lichenized fungi, in terms of molecular weight and UV spectrum. Myelochroa entotheiochroa and Pseudoparmelia cubensis, known for their high secalonic acid A content, were selected as reference samples. A comparison of chromatographic and spectrometric data of secalonic acid A and the pigment subauriferin confirmed their identity. Key words: high-performance liquid chromatography, mass spectrometry.