The article presents the results of studies aimed at assessing the possibility and effectiveness of using hydro-removal ash, hereinafter referred to as HRA, as a component of composite cement binders. The structural characteristics of the HRA of the largest thermal power plants located in the Irkutsk region such as: TPP-10, TPP-9, TPP-11, Novo-Irkutsk TPP are studied and presented in the article; the following methods are used: X-ray structural analysis, X-ray fluorescence analysis, IR spectroscopy, elemental analysis, Romanov spectroscopy, laser diffraction. In the course of the research, the most rational ways of obtaining composite binders by combined and separate grinding using HRA and Portland cement CEMI-42.5N, which meets the require-ments of GOST 31108-2020, were established. The optimal values of specific surface area, water demand, pozzolanic activity and grindability coefficient of HRA have been determined, which in turn ensure the highest strength indicators of cement stone on a composite binder. In particular: the compressive strength of cement stone of a composite binder consisting of 50% HRA exceeds the strength of cement stone on ordinary Portland cement at the age of 28 days and is 110 MPa versus 93 MPa, respectively. The achieved strength indicators obtained as a result of the research allow us to draw a conclusion about the effectiveness of using HRA as a component of composite cement binder and to recommend the developed compositions for use in commercial concretes and mortars, taking into account the final requirements for the final quality indicators.