The inclusion complex of cationic beta-cyclodextrin and 2-phosphonobutane-1,2,4-tricarboxylic acid was prepared as a highly efficient acid composition in the process of oil wells acidizing for enhancing oil recovery. In the progress of acid stimulation, the inclusion complex could not only inhibit clay swelling, but also retard the acid-rock reaction rate and self-regulate dissolution rate. These advantages present significant potential applications to clear acid channel and prolong acidizing distance of real-world oil wells, which contributes to enhancing oil recovery. In addition, a possible interaction mechanism of the novel acid system in the progress of acid treatments was provided. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.