The results of thermal studies of some derivatives of dithiophosphoric, xanthogenic, dithiocarbamic acids are presented. The thermal parameters of the compounds were determined both in pure form and in the presence of iron and copper powders. Their chemical activity with respect to iron and copper was studied. It has been found that the temperature at which the thermal stability of the studied compounds is maintained exceeds 170⁰С, and they are chemically active with respect to iron and copper: the lower the interaction temperature within the same row with iron and copper and the lower its mass loss corresponding to this temperature, the more effective it is like an extreme pressure (EP) additive. It has been found that compounds of the same series, reacting with metal by the type of synchronous and exchange reactions, have better indicators of extreme pressure properties than compounds interacting with metal by the type of asynchronous reaction

doi.org/10.32737/0005-2531-2023-4-97-103