We conducted tracer experiments on core samples from six different carbonates to study the flow of aciefluid through the porous media of carbonate rocks and correlate the carbonate pore classes to the acid response. Pore structures were characterized by section analysis, high pressure mercury injection tests, and nuclear magnetic resonance measureinents; thineralogy was determined by X-ray diffraction. Tracer concentration profiles were analyzed to quantify the carbonate pore-stale heterogeneity. The heterogeneity is expressed using a parameter f-the available fraction of pore stiticture contributing,M the flow. From the results, different characterization methods could be connected to the acid fluid flow through the porous media of carbonate rocks. h was also found that the response of the add depends on the carbonate pore classes. Applications include the design of matrix acid treatments in carbonate rocks.