This paper presents the results of the experimental investigations into the effectiveness of latex based "smart cement" in remediating wellbore related CO 2 leakage. Porosity, N 2 and CO 2 permeabilities, mechanical and elastic properties of the smart cement mixtures developed were determined using core samples. The effectiveness of the smart cement in reducing the cement permeability was assessed through a series of core flooding experiments and by comparing the results with those of Class G Portland cement. A full scale laboratory wellbore test rig was used to investigate the interactions between CO 2 and latex-cement at realistic wellbore conditions. Permeability response of the "smart cement" and microannulus were measured with N 2 and CO 2 at flow rates representative of likely CO 2 leakage rates at storage sites and the results are reported.