The electrochemical modification of activated carbons (AC) by a conducting polymer polypyrrole (PPy) has a substantial effect on the AC structure characteristics, electrochemical properties, and adsorption activity with respect to natural substances (by the example of free hemoglobin). Using the method of standard contact porosimetry (SCP), the porous structure and hydrophilic–hydrophobic properties are studied for the activated carbon SKT-6A, the [SKT-6A/PPy/Cl–] composite, and individual polypyrrole. The chemistry of the activated carbon surface is studied by the standardized Boehm method. It is shown that the nature of activated carbon and its initial surface substantially affect the character of its interaction with the conducting polymer polypyrrole. The effect of such modification on the AC surface chemistry should be considered in aggregate by taking into account each component of such modification. The increase in the sorption ability of [AC/PPy/Cl–] composites with respect to hemoglobin is largely associated with the stronger hydrophilicity of polypyrrole as compared with activated carbons.