Relevance. Acid treatments of carbonate reservoirs are widely used to intensify oil inflow to producers. In practice the rate of acid injection during such treatments widely varies. At certain flow rates, the acid-rock reaction mode leads to the formation of separate extended wormhole channels. This mode corresponds to the maximum increase in well productivity. Therefore, it is important to conduct experimental research determining acid injection volume before the wormhole breakthrough on the core outlet from the specific injection velocity. Currently, research has been conducted for calcites, the study of the reaction in dolomites remains a relevant issue. Aim. To assess the effect of acid concentration on the critical values of the injection rate and correspondent volume causing wormholes formation. Methods. An installation for determining phase permeability is used to conduct filtration experiments on acid injection into a core sample. Samples of standard sizes with a dolomite content above 90% are used. The acid injection volume before the wormhole breakthrough is measured at different acid injection rates with several acid concentrations. Acid breakthrough is detected by the core inlet pressure steep drop. Results and conclusions. Experimental dependencies of the injection pore volume before acid breakthrough on the outlet of dolomite samples from the injection rate for hydrochloric acid with 9, 12, and 15% concentrations were obtained. It is shown that these dependencies have a nonlinear character with a minimum corresponding to the critical injection velocity. This result is confirmed by early experiments conducted on calcite rocks. It was found that an increase in acid concentration leads to a decrease of the injected pore volume to acid breakthrough and critical rate corresponding to wormholes formation.