Deep saline aquifers have the largest estimated capacity for CO₂ storage among many geologic storage options. Obtaining insight into possible geochemically induced changes to the host CO₂ storage rocks such as permeability and porosity will enable us to gain knowledge on long-term reservoir behavior under CO₂ storage conditions. An experimental study of the interaction of CO₂/brine/rock was conducted in a static system under CO₂ storage conditions. Chemical interactions in the Cedar Keys-Lawson Formation dolostone during exposure to CO₂ and brine under sequestration conditions were studied. Samples were exposed to the simulated in-situ reaction conditions for six, twelve, and twenty-four months. The samples were exposed to a model brine at 55 °C and CO₂ pressure of 23.8 MPa (3,500 psig). Computed tomography (CT), x-ray diffraction (XRD), scanning electron microscopy (SEM)-energy dispersive x-ray spectroscopy (EDS), brine composition, core porosity, and core permeability analyses were conducted prior to and after the exposure experiments. The core samples showed a decrease of porosity after they were exposed to CO₂-saturated brine for the period of six, twelve and twenty-four months. This observation implies that mineral precipitation could occur in the host rock thus changing its characteristics for CO₂ storage over time. The measured permeabilities for six- and twelve-month exposure samples show an increase. The CT images of the pore space clearly indicate the degree of dissolution that occurred during the six-month exposure. It is noted that the dolomite, anhydrite, and gypsum dissolution that occurred during the six-month exposure could have enhanced the connectivity between voids. This may contribute to the increase of permeability after the CO₂/brine exposure. However, the 23% decrease of permeability after the twenty-four month exposure experiment likely relates to NaCl and mineral precipitation blocking the connectivity of pores resulting in the observed decrease in permeability.