The article is dedicated to the blessed memory of the outstanding scientist, teacher-mentor, professor, doctor of biological sciences Tatyana Alekseevna Sokolova. The scientific community knows and will always remember Tatyana Alekseevna as an authoritative specialist in the field of soil science and mineralogy. The scope of her interests in the scientific and educational system is wide and diverse. One of the fundamental areas of work is the problems of soil acidity. The presented material contains some components of the creative heritage of T.A. Sokolova in the aspect of current research and prospects for its development. In particular, attention is drawn to the nature of the acidity of highly acidic soils (pHKCl <3.3, pHH2O <4.4). The specificity of the formation of the acid-base state of these objects is shown using soils of different genesis as an example. The reasons for the low accuracy and reproducibility of the results of measuring the exchangeable acidity of highly acidic soils are revealed. Recommendations for improving the quality of measurements are given.